You can type "/a" <started by hitting the tab button> and it will scroll through all the "a" commands.

/tell <player> <message> (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 <player> <message> - 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 <message> (alias '/me') - Creates an emote.
/exit - Quit the game.
/follow (alias '/f') - Target a player and type this. You will follow that player.
/ignore <player> - Ignore player. The Ignore command will also ignore emotes.
/unignore <player> - Turn off ignore player.
/invite <player> (alias '/inv') - Invite a player to your party.
/logout (alias '/camp') - Log out of the game.
/party <message> (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 <X> [Y] (alias '/roll') - 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. Using /random will send the text to your party or raid wherever they are instead of the local area around the player that used /random.
/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 <message> (alias '/s') - Send a message to people near you.
/sit - When standing, your character will sit.
/stand - When sitting, your character will stand.
/who - Lists the players online.
/yell <message> (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.
/ckick - "/ckick ChannelName CharacterName"
/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 <channel> <password> - Change password.
/rw - Send raid warning text. This is only available to raid leaders and assistants.
/readycheck - A ready check sends an "Are you ready?" Yes/No dialogue to all players in the raid. The raid leader will get feedback in 30 seconds on all the players who were not ready or who did not respond. Only raid leaders can do this.
/raidinfo - shows remaining time on saved raid instances. Also shows an ID to compare with other players (if you have the same saved ID as them, you will go into the same instance)

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.

/attacktarget
/bye
/charge
/cheer
/congratulate
/flee
/flirt
/followme
/healme
/hello
/helpme
/incoming
/no
/nod
/oom
/openfire
/rasp
/silly
/thank
/wait
/welcome