What Is Gaim?
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.
Gaim supports many features of the various networks, such as file transfer, away messages, typing notification, and MSN window closing notification. It also goes beyond that and provides many unique features. A few popular features are Buddy Pounces, which give the ability to notify you, send a message, play a sound, or run a program when a specific buddy goes away, signs online, or returns from idle; and plugins, consisting of text replacement, a buddy ticker, extended message notification, iconify on away, spell checking, tabbed conversations, and more.
Gaim runs on a number of platforms, including Windows, Linux, and Qtopia (Sharp Zaurus and iPaq).
Gaim integrates well with GNOME 2 and KDE 3.1's system tray, as well as Windows's own system tray. This allows you to work with Gaim without requiring the buddy list window to be up at all times.
Download it from Here
Also you can try Eyeball Chat
Eyeball Chat lets you...
Video chat live with friends and family
Share video messages, music and photos
Meet new people in the Eyeball Chat Rooms
Send video and text messages to your AIM, MSN and Yahoo! buddies
Communicate securely and privately with SSL encryption
Download it here