Microsoft Corporation - 41.9 MB - Freeware
Talk with friends and family for free over the World
Flagship Industries, Inc - 3.61 MB - Freeware
Very powerful, cross-platform VoIP group communications utility
Cerulean Studios - 14.92 MB - Freeware
Chat with other Trillian users or those on Facebook, Twitter, Google...
Miranda IM - 7.63 MB - Open Source
Faster and easier instant messenger with support for multiple protocols
Peter Zelezny - 975.67 KB - Open Source
Allows you to join multiple IRC channels (chat rooms) at the same time
Tencent, Inc. - 33.2 MB - Freeware
Free text messaging and free video calls with more than 500 million people!