Pidgin is an easy to use, multi-protocol instant messaging client with a tabbed interface, sounds, and more customizable items. Supports a long list of networks, including AOL, Yahoo, MSN, ICQ, Jabber and IRC, and 85 languages worldwide. A wide variety of plug-ins are available to add more features, including networking, security, interface configuration, and more. Download Link: Pidgin Portable
Miranda IM is an extensible client, instant messenger customizable compatible with AIM, ICQ, IRC, Gadu Gadu, MSN, Yahoo and Jabber. The program can support more protocols through a plugin system expanded to include Netsend, Skype, Facebook, etc. and the complement system may add other features like skins, an RSS reader, weather alert, world clock, secure messaging, etc. Download Link: Miranda IM Portable
