I have just spent an hour or so evaluating a selection of XMPP (Jabber) clients, including Pidgin, Miranda, Trillian and Pandion. After some playing I have settled on Pidgin for the moment. It is a multi-protocol client which supports a whole range of services. I currently have it set up for AIM, Yahoo, Google Talk, and my own Jabber server. What I would really like is one which also supports Skype IM – I use that a lot for work.
For now I have fully installed Pidgin, but I am very interested in the possibility of creating a portable version which runs from a USB drive.