Pidgin

Pidgin (formerly GAIM) is a multi-platform instant messaging client that allows you to connect with all your buddies from a single messenger, even if they are using different networks. It supports MSN, AIM,ICQ, Yahoo, IRC, Groupwise, QQ, SILC, SIMPLE, Sametime and XMPP. You can login to multiple messenger accounts at one, allowing you to chat with your buddies on Yahoo, ICQ and MSN (for example) at the same time. It supports all of the standard messenger features including online status, file transfers, contact blocking, contact aliases, buddy groups, status notifications and more. Pidgin also supports plug-ins to add additional functionality.

Platform:
Win (All)

Cons: Cons: Does not support video or audio chat; limited documentation
Pros: Pros: Supports multiple messenger services; chat on multiple networks at once
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