Discuss Pidgin (formerly known as Gaim), the open source, multi-protocol IM that can connect to just about anything.

What is Google Talk? It's the new instant messenger from none-other than Google. Got it? Want it? Discuss it... here!

AOL-owned ICQ ("I seek you") is the venerable "Swiss Army knife" of instant messengers.

Internet Relay Chat... the grand-daddy of chat, and still uncharted frontier for many.

Skype gives you free PC-to-PC voice calls, and the option of paid PC-to-phone calls using VoIP technology.

Compatible with AIM, MSN, Yahoo, ICQ, IRC and others.