Instant Messengers

[SOS]

I use AoL Instant Messenger and the yahoo! Instant messenger. Both are free and easy to use.
AOL (http://www.aol.com)
Yahoo! (http://www.yahoo.com)

[Ranma Saotome]

AIM is good, but Odigo is great... www.odigo.com (http://www.odigo.com)

[SOS]

Try this out if you use many instant messengers and want just one program to use them all:
Trillian Instant Messenger (http://www.trillian.cc/)

Communicate with Flexibility and Style.
Trillian is everything you need for instant messaging. Connect to ICQ, AOL Instant Messenger, MSN Messenger, Yahoo! Messenger and IRC in a single, sleek and slim interface.

[Stingray]

Trillian is the best out there!!, I use it 24/7

new version is out 0.724