Most of these commands can be found in the file README.txt inside the game's folder.

Host-only:
/ban [PlayerName] - Kicks a player and adds their IP address to banned.txt. IP addresses will have to be manually removed from this file to unban.
/kick [PlayerName] - Kicks a player from the server.
/banid [Player ID] - (Host only) Kicks and bans a player by their ID number. Hold F3 to see ID numbers hover over players.
/kickid [Player ID] - (Host only) Kicks a player by their ID number.
/uptime - (Host only) Displays the server up time.
/blink - (Host only) Teleports the host player to the mouse.
/pause - (Host only) Pauses the server.
/unpause - (Host only) Unpauses the server.
/start - (Host only) Skips the count down for Zombrains and Survival mode
/changemap [mapfile] - (Host only) Changes the map to the specified file name.
/lobby - (Host only) Attempts to connect to the server list if its disconnected.
/roundrestart - (Host only) Restarts the round in TDM. Works in other modes but might break something.
/addbot - (Host only) Adds a bot in Deathmatch/Zombrains
/addbot [blue/red] - (Host only) Adds a bot in a team game.
/botskick - (Host only) Kicks all bots.
/autobalance - (Host only) Initiate autobalance
/checkpoint - (Host only) Moves you to the nearest check point on Climb mode.
/restartmap - Restarts the map, or changes to the new map if a vote succeeded (Maybe)
/zombie [0/1] - (Host only) Enables or disables zombies in any mode but Zombrains.

/voteban [PlayerName] - Initiates a vote ban. Votes must exceed a certain percent to succeed. Vote bans can not be called on the host.
/votemap [map filename] - Searches for the map file, and initiates a vote to change to it when found.
/nextmap - Tells you what the next map is.
/clearghosts - Deletes all ghosts in Climb mode

/kill - Commit suicide.
/barf - Blow chunks.
/smoke - Smoke your life away.
/yeehaw - Yeehaw?
/warcry - Premium
/letsgo - Premium

Another way to do some of the taunts (barf, yeehaw, ...) is to press CTRL + V/B/N/M.

First: to use that you need to go to options,controls,misc and in chat binding press ctrl,And now you can use the ctrl

Team-oriented
CTRL + 1 - "MEDIC!"
CTRL + 2 - T"hey are going high."
CTRL + 3 - "They are going low."
CTRL + 4 - "Is our base secure?"
CTRL + 5 - "Our base is under attack!"
CTRL + 6 - "I will defend."
CTRL + 7 - "I will attack."
CTRL + 8 - "I need ammo."
CTRL + 9 - "Follow me."
CTRL + 0 - "Good work!"

Random
CTRL + Q - "Anytime."
CTRL + W - "Help!"
CTRL + E - "Ooops!"
CTRL + R - "Hello."
CTRL + T - "Yippee ki-yay!"
CTRL + Y - "Woohoo!"
CTRL + U - "Gross!"
CTRL + I - "Die!"
CTRL + O - "HAHAHAHAHAHAHA"
CTRL + P - "Sniper!"
CTRL + A - "Yeah"
CTRL + S - "Thanks!"
CTRL + D - "No!"
CTRL + F - "Bye."
CTRL + G - "Good game."
CTRL + H - "Don't worry, you're doing fine."
CTRL + J - "Booo-logna!"
CTRL + K - "Get bent!"
CTRL + L - "Balance the teams!"
CTRL + Z - "F12"
CTRL + X - "F11"
CTRL + C - "Hurraaaa!!!"
CTRL + V - Yeehaw! Taunt
CTRL + B - Drink Taunt
CTRL + N - Barf Taunt"
CTRL + M - Smoke Taunt