Miranda IM is an instant messaging client designed to be resource efficient and easy to use. Portable version also available.

Miranda IM uses very limited memory, requires no installation and can easily be carried around on a single floppy disc.

The powerful plugin system makes Miranda IM extremely flexible. Only the most basic features are built in, but there are currently more than 130 plugins available for download that allows users to extend the functionality in Miranda IM. Plugins can be installed to add support for ICQ, MSN, Yahoo, Jabber, Gadu-Gadu, Tlen, netsend, and other protocols.

Available protocols:

ICQ
IRC
Facebook
AIM
MSN
IAX
Jabber
Yahoo
Gadu-Gadu
Tlen
Netsend
And more...