Pidgin

Pidgin screenshots

Choosing Pidgin as messenger has an advantages on those who uses different IMs
Some of the supported protocols
Pidgin 2.5 : Some of the supported protocols

Alternative downloads

Google Talk
1.0.0.105
FREE
Instant messaging and chatting application.
Pidgin SIPE plug-in
1.12
FREE
Helps to replace your Microsoft Office Communicator client with Pidgin.
Chat Assistant
2.0
This is an amusing chat tool can make your chat more interesting.