Gaim is a multi-protocol instant messaging (IM) client for Linux, BSD, MacOS X, and Windows. It is compatible with AIM and ICQ (Oscar protocol), MSN Messenger, Yahoo!, IRC, Jabber, Gadu-Gadu, SILC, GroupWise Messenger, and Zephyr networks.
Gaim users can log in to multiple accounts on multiple IM networks simultaneously. This means that you can be chatting with friends on AOL Instant Messenger, talking to a friend on Yahoo Messenger, and sitting in an IRC channel all at the same time.
Meebo is a multi-protocol web-based messenger. You can use Meebo to sign-in to AIM/ICQ, MSN Messenger, Yahoo! Messenger and Google Talk or other Jabber servers -- all at the same time. Meebo uses an innovative AJAX-powered interface that feels much like a real application, even though it's all web based.
Meetro is the messenger that helps you find people. Tells how close they are (If using Meetro also) and you can chat with your AIM, ICQ, Yahoo!, and MSN buddies! To use you must make an account which you can do by going here.
Unlike Trillian, Gaim, etc which ONLY let you access the various other IM programs, Paltalk does that too (linking to YM, MSN, AIM, ICQ) but is also a complete IM program (including voice and video) itself.
Probably 95% of PalTalk users don't even realise its "multi-protocol" side - they just use PalTalk itself.
The free version has quite a lot of adverts, AND limits on webcam viewing, but is still very usable.
This program has an excellent network of Chat Rooms, mainly with voice, and fairly well categorised and policed.
Trillian is the Swiss Army knife of instant messaging. It connects to AIM, MSN, ICQ, Yahoo!, and even IRC. Trillian comes in two flavors; Trillian Basic is free, while Trillian Pro requires a purchase, but includes plug-in capabilities that make it very attractive to anyone who regularly uses multiple instant messaging networks.
For more information on Trillian, visit our Trillian Center.
Call friends & family around the world using the all new Yahoo! Messenger (8.1)
IM With Friends on Windows Live Messenger ~ Have all your IM friends in one place. Ping-away with people who use Windows Live Messenger. They'll also be on your contact list so you can see when they're online
Plug-in the fun ~ Add your personal touch. Handy plug-ins deliver the stuff you want to your Messenger. Choose Yahoo! plug-ins or ones from eBay, Amazon.com, and more.