Google Talk 1.0.0.105 Enables you to call or send instant messages to your friends for free–anytime, anywhere in the world 1.27 MB | Windows All | Freeware | Rating: Very Good (4.3/5) | Downloads: 327,026

AOL Instant Messenger (AIM) 6.5.7.18 Beta An IM application that users to communicate via private, personalized text messages 13.2 MB | Windows All | Adware | Rating: Very Good (4.1/5) | Downloads: 118,159

IntraMessenger 1.03Q Instant Messenger at office (for LAN or internet) - server PHP/MySQL 2.43 MB | Windows All | Freeware | Rating: Very Good (4.0/5) | Downloads: 617

Yahoo! Messenger Vista Preview 2007.12.06.421 / 9.0.0.907 Beta / 8.1.0.421 Instant messaging allows you to quickly exchange messages with your online friends 12.7 MB | Windows All | Adware | Rating: Very Good (4.1/5) | Downloads: 2,204,391

LanTalk NET 3.3 Build 5273 Instant messenger for LAN, WAN and Internet (no server) 968 KB | Windows All | Trial | Rating: Very Good (4.0/5) | Downloads: 6,725

ICQ 6.0 Build 6039 ICQ Lite is the slimmed down version of the popular ICQ instant messenger 13.4 MB | Windows All | Adware | Rating: Good (3.9/5) | Downloads: 24,229

Yahoo Ghost! 2.0.37 Use Multi Yahoo IDs at one Messenger, Remove Yahoo Advertisment & alot of more... 36 KB | Windows All | Freeware | Rating: Very Good (4.5/5) | Downloads: 3,691

Windows Live Messenger 9.0.1407.1107 | The latest version of Windows Live Messenger from Microsoft99,141 downloads | Rating 4.38/5

Microsoft Office Communicator 2007 2.0.6362.0 Makes it easier for information workers to find and connect with their colleagues and coworkers from anywhere 9.62 MB | Windows 2K/XP/2003/Vista | Freeware | Rating: Good (3.1/5) | Downloads: 4,520