You can type "/a"  and it will scroll through all the "a" commands.

/tell   (alias '/t') - Send a player a private message. You can scroll through all the people that whispered you recently by typing on the tab key.
/w   - Send a player a private message. You can scroll through all the people that whispered you recently by typing on the tab key.
/chathelp (alias '/chat') - List of chat commands
/em  (alias '/me') - Creates an emote
/exit - Quit the game
/follow (alias '/f') - Target a player and type this. You will follow that player.
/ghelp - For a list of guild commands
/invite  (alias '/inv') - Invite a player to your party.
/logout - Log out of the game
/party  (alias '/p') - Sends a message to party chat
/played - Reports the amount of time you've played the game with that character.
/pvp - Enable your character to be attacked by other players in Player vs. Player combat.
/random  [Y]: Generates a random number between X and Y, if Y isn't specified, then it will generate a number between 1 and X. This is very useful to determine who's going to have the right to loot a chest or harvest a resource.
/r - Reply to the last tell/private message. You can scroll through all the people that whispered you recently by typing on the tab key.
/say  (alias '/s') - Send a message to people near you
/sit - When standing, your character will sit. Your character regains health more quickly when sitting.
/stand - When sitting, your character will stand.
/who - Lists the players online.
/yell  (alias '/y') - Yells a message to the area around. Many players consider this to be "spam" so use it sparingly.

/cast allows you to cast spells by name. Type /cast (spell subtext) - Example: "/cast Fireball (Rank 1)". To add spell casting to a macro you can type it manually or shift-click a spell in your spell book to add the proper /cast line to the macro.

Chat Commands

    /#, /c, /csay - Send text to channel # (e.g. /1 Hi!)
    /announcements, /ann - Toggle join/leave announcements on a channel
    /afk, /dnd - Set your Away From Keyboard or Do Not Disturb flags
    /ban, /unban - Ban/unban a player from a channel
    /chatlist, /chatwho, /chatinfo [channel] - List channels, or channel members
    /cinvite, /chatinvite - Invite a player to a channel
    /join, /channel, /chan - Join a channel
    /kick - Kick a player off a channel
    /leave, /chatleave, /chatexit [channel] - Leave a channel (or all channels)
    /mod, /moderator, /unmod, /unmoderator - Change a player's moderator status
    /moderate - Toggle moderation on a channel
    /mute, /squelch, /unvoice, /unmute, /unsquelch, /voice - Change a player's permission
    /password, /pass   - Change password

Guild Commands
Check out our guild page for guild commands.

Voice (Sounds)
The following will play a sound! There are two to three variations for each one. The voices will be different depending on your character.

    /v help
    /v inc - Incoming. You type this to warn your party that a monster is coming to attack
    /v charge
    /v flee
    /v attack
    /v oom - Out of mana, low on mana
    /v fol - Follow Me
    /v wait
    /v heal
    /v cheer
    /v fire
    /v rasp - Sticking your tongue out sound
 

Command     Usage     Description
gxRestart       Restart the graphics engine.
reloadUI       Reloads the user interface.
light    light [0-1]    Toggles light on/off.
fog    fog [0-1]    Toggles fog on/off.
DepthTest    depthtest [0-1]    Toggles depthtest on/off.
DepthSet    depthset [0-1]    Toggles depthwriting on/off.
culling    culling [0-1]    Toggles backface culling on/off.
dblbuffer    dblbuffer [0-1]    Toggles double buffering on/off.
resxy    resxy [x] [y]    Sets the screen resolution to x by y pixels.
resmode    resmode [0-3]    Sets the screen resolution mode x.
bitdepth    bitdepth [16 or 32]    Sets the color depth 16 or 32 bits (You need to restart the game after change).
3dapi    3dapi [OpenGL or Direc3d]    3dapi toggles the 3D API between OpenGL and Direct3D (You need to restart the game after change).
showDetailDoodads    showdetaildoodads [0-1]    Toggles the showing of detailing doodads (grass, flowers) on/off.
maxLOD    maxLOD [0-10]    Set the maximum land shape value.
showCull    maxLOD [0-1]    Toggle culling on/off.
setShadow    setShadow [0-1]    Shadow colors must be in range (0.0,1.0).
mapObjLightMode       Toggle between vertex light / lightmaps.
waterShow    watershow [0-1]    Toggles viewing water on/off.
waterMaxLOD    maxLOD [0-10]    Set the maximum water shape value.
waterWaves    waterwaves [0-1]    Toggles water waves on/off.
waterSpecular    waterspecular [0-1]    Toggles water specularity on/off.
waterRipples    waterripples [0-1]    Toggles water ripples on/off.
waterParticulates    waterparticulates [0-1]    Toggles water particulates on/off.
showShadow    showshadow [0-1]    Toggles terrain shadows on/off.
showLowDetail    showlowdetail [0-1]    Toggles showing low detail on/off.
showSimpleDoodads    showsimpledoodads [0-1]    Toggles showing "simple" doodads on/off.
detailDoodadAlpha    showsimpledoodads [0-255]    Set the doodad alpha level (Lower value is better).
shadowLOD    shadowlod [0-1]    Set the shadow LOD.
showplayer    showplayer [0-1]    Toggles showing your character on/off.
motionBlend    motionblend [0-1]    Toggles motion blending on/off.
SkyCloudLayers    skycloudlayers [0.0-1.0]    Set the sky cloud layers.
SkyCloudDensity    skycloudlayers [0.0-1.0]    Set the sky cloud density.
SkySunGlare    skysunglare [0-1]    Toggles sun glare on/off.
SkyShow    skyshow [0-1]    Toggles sky on/off.

Command    Usage    Description
HeapUsage       Displays a list of the heaps in use.
ObjUsage       Displays the object manager list status.
newleader       Sets a new leader in your current group.
lootmethod    lootmethod [method]
Method: freeforall / roundrobin / master    Toggles your loot method.
cast    cast [skillname]    Cast a spell.
cancelaura    cancelaura [index]    Cancels an aura given the aura's index, not auraID.
spellstring    spellstring [string]    Opens up an edit box for the specified spell.
highlightcolor    highlightcolor [alpha 0-255] [red 0-255] [green 0-255] [blue 0-255]    Change the highlighted text color.
playercombatlogdebug    playercombatlogdebug [0-1]    Toggles combat logging on/off.
invite    invite [player]    Invites a player to join your group.
accept       Accepts the group invitation.
decline       Declines the group invitation.
disband       Disband your current group (Must be group leader).
uninvite    uninvite [player]    Remove a member from your group (Must be group leader).
repopme    repopme [0-1]    Repops you when you're dead.
who       Displays a list of the other users on the server.
undressme       Strips your character of all of its equipment.
acceptres       Accept resurrection request.
declineres       Decline resurrection request.
guildcreate    guildcreate [name]    Creates a guild.
friends       Displays your current friends list.
addfriend    addfriend [name]    Adds specified friend to your friends list.
removefriend    removefriend [name]    Removes specified friend from your friends list.
deathbind    deathbind [bindstoneid]    Binds you to the inputted bindstoneID.
recharge       Instantly fully heal yourself.

Command     Usage     Description
help    help [topic]    Displays help information about the requested category.
quit       Exits the program to desktop.
ver       Displays the current version and build date.
set    set [variable] [value]    Sets a variable to the defined value.
cvar_reset    cvar_reset [cvar]    Sets the value of a CVar to it's startup value.
cvar_default       Sets the value of a CVar to it's color coded default value.
cvarlist       Lists every CVar.
gxColorBits    gxcolorbits [16, 24, or 30]
gxrestart    Sets the color bits to be used.
gxDepthBits    gxdepthbits [16, 24, or 32]
gxrestart    Sets the color depth to be used.
gxResolution    gxresolution [resolution]
gxrestart    Sets the resolution to be used.
gxRefresh    gxrefresh [refreshrate]
gxrestart    Sets the refresh rate.
gxApi    gxapi [api]
gxrestart    Sets the 3d api to render.
gxVSync    gxvsync [0-1]
gxrestart    Toggles vertical sync on/off.
gxWindow    gxwindow [0-1]
gxrestart    Toggles windowed mode on/off.
hwDetect    hwdetect [0-1]    Toggles hardware detection on/off.
settings    settings [0-1]    Returns information about the console.
lod    lod [0-1]    Toggles land smoothing on/off.
fullAlpha    fullalpha [0-1]    Toggles full alpha on doodads on/off.
doodadAnim    doodadanim [0-1]    Toggles doodad animation on/off.
mapShadows    mapshadows [0-1]    Toggles terrain shadows on/off.
lightMaps       Always returns (null).
lodDist    lodDist [50-250]    Sets the land smoothing maximum distance from player in feet.
SmallCull    smallcull [0.001-2.0]    Sets the doodad culling level.
DistCull    distcull [1.0-888.888916]    
MaxLights    maxlights [0-8]    Sets the maximum number of simultaenous light sources.
shadowLevel    shadowlevel [0-1]    Toggles the shadow mip level on/off.
alphaLevel    alphalevel [0-1]    Toggles the alpha mip level on/off.
texLodBias    textlodbias [-1.0 - 1.0]    Unknown (?).
detailDensity    detaildensity [1-128]    Sets doodad density levels.
farclip    farclip [177-777]    Sets the maximum distance you can see.
nearclip    nearclip [177-777]    Sets the maximum distance you can see.
fov    fov [1-179]    Sets your characters field of view.
specular    specular [0-1]    Toggles specular shading on/off.
pixelShaders    pixelshaders [0-1]    Toggles pixel shading on/off.
particleDensity    particledensity [0.3-1]    Sets particle density level.
unitDrawDist    unitdrawdist [20-150]    Sets the unit draw maximum distance.
waterLOD    waterlod [0-1]    Toggles water smoothing effects on/off.
baseMip    basemip [0-1]    Toggles basemip on/off.
anisotropic    anisotropic [1-16]    Sets anisotropic filtering level.
textureLodDist    textureloddist [80-777]    Sets the maximum distance for the game to texture.
Errors    errors [0-1]    Toggles error display on/off.
ErrorFilter    errorfilter [filter]
Filters: general / world / ui / animation / models / objects / all    Use "except" to invert mask.
debugTargetInfo    debugtargetinfo [0-1]    Toggles displaying target debugging information tooltips on/off.
showGUIDs    showguids [0-1]    Toggles displaying GUID tooltips on/off.
realmName       Displays the realm name.
realmAddress       Displays the realm address.
profanityFilter    profanityfilter [0-1]    Toggles the builtin profanity filter on/off.
EnableMusic    enablemusic [0-1]    
EnableSound    enablesound [0-1]    Toggles enabling sound on/off.
realmList       Shows a list of all current realms.
mouseInvertYaw    mouseinvertyaw [0-1]    Toggles mouse inversion on/off.
mouseInvertPitch    mouseinvertpitch [0-100]    Sets mouse inversion pitch level.
EnableGroupSpeech    enablegroupspeech [0-1]    Toggles enabling hearing group speech on/off.
EnableErrorSpeech    enableerrorspeech [0-1]    Toggles enabling error sounds on/off.
EnableAmbience    enableambience [0-1]    Toggles enabling ambience sounds on/off.
MapWaterSounds    mapwatersounds [0-1]    Toggles enabling water sounds on/off.
statusBarText    statusbartext [0-1]    Toggles status bar text on/off.
combatLogOn    combatlogon [0-1]    Toggles combat logging on/off.
showsmartrects    showsmartrects [0-1]    Toggles showing "smart" rectangles on/off.
weapontrails    showsmartrects [0-1]    Toggles weapon trails on/off.
ObjectSelectionCircle    objectselectioncircle [0-1]    Toggles the object selection circle or not. Turning it off will be confusing.
FootstepSounds    footstepsounds [0-1]    Toggles playing footstep sounds on/off.
showfootprints    showfootprints [0-1]    Toggles showing footprints on/off.
showfootprintparticles    showfootprintparticles [0-1]    Toggles showing footprints particulates on/off.
ShowBreath    showbreath [0-1]    Toggles showing characters breath on/off.
violenceLevel    violencelevel [0-5]    Sets the violence level.
SkyCloudLOD    skycloudlod [0-1]    Toggles sky texture effects/smoothing on/off.
logout       Logs you out of the current realm.
script    script    Executes the specifed config file on the client.

Command     Usage     Description
HeapUsage       Displays a list of the heaps in use.
ObjUsage       Displays the object manager list status.
newleader       Sets a new leader in your current group.
lootmethod    lootmethod [method]
Method: freeforall / roundrobin / master    Toggles your loot method.
cast    cast [skillname]    Cast a spell.
cancelaura    cancelaura [index]    Cancels an aura given the aura's index, not auraID.
spellstring    spellstring [string]    Opens up an edit box for the specified spell.
highlightcolor    highlightcolor [alpha 0-255] [red 0-255] [green 0-255] [blue 0-255]    Change the highlighted text color.
playercombatlogdebug    playercombatlogdebug [0-1]    Toggles combat logging on/off.
invite    invite [player]    Invites a player to join your group.
accept       Accepts the group invitation.
decline       Declines the group invitation.
disband       Disband your current group (Must be group leader).
uninvite    uninvite [player]    Remove a member from your group (Must be group leader).
repopme    repopme [0-1]    Repops you when you're dead.
who       Displays a list of the other users on the server.
undressme       Strips your character of all of its equipment.
acceptres       Accept resurrection request.
declineres       Decline resurrection request.
guildcreate    guildcreate [name]    Creates a guild.
friends       Displays your current friends list.
addfriend    addfriend [name]    Adds specified friend to your friends list.
removefriend    removefriend [name]    Removes specified friend from your friends list.
deathbind    deathbind [bindstoneid]    Binds you to the inputted bindstoneID.
recharge       Instantly fully heal yourself.

-- ChrisWeiss - 11 Feb 2005