For doing over-the-counter trades, you probably want to get yourself set up with GPG and start using that. When trading on the forums, you might think you are trading with the trusted forum member but in reality it could be a compromised forum account and you are about to send your bitcoins into some scammer's pocket. With the -otc Web of Trust (WoT), if the person has authenticated, you then are nearly guaranteed that the party you are trading with is truly the same party whose trust history is well documented.
- http://www.Bitcoin-OTC.com
- http://webchat.freenode.net/?channels=#bitcoin-otc-foyer
- http://www.bitcoin-otc.com/viewratings.php
There's always IRC chat, Skype, GibberBot, text messaging, and Crypto.cat
- https://crypto.cat