Miranda IM Portable
compact, portable instant messaging
Miranda IM Portable is a customizable instant messaging client.
Features
Miranda IM is a multi protocol instant messenger client for Windows. Miranda IM uses very little memory and is extremely fast. It supports ICQ, AIM, MSN, Jabber, Yahoo, IRC and more. Functionality can be greatly enhanced with an extensive set of plugins (currently over 350) as well. The interface and setup is a bit more involved than other IM clients like Pidgin Portable, but the customization options available are richer
https://portableapps.com