Jabphone (beta!) allows you to call your friends on the phone using the Jabber Instant Messaging system.

Portable Gaim is the versatile Gaim instant messaging client packaged as a portable app, so you can take your IM settings and buddy lists with you. The Off-the-record plugin is also included for secure, encrypted messaging.

After Google's acquisition of a five percent stake in AOL last week, both companies decided that it would be advantageous to implement complete interoperability between Google Talk and AIM.

Changelog for Gaim 2.0

The MAKEbot is a AIM/iChat buddy you add to your list.

Using Google Talk with GAIM users

Open source software for IM programs