JBother is a Jabber client written in pure Java (1.4.x). It supports groupchat in a tabbed window, multiple resources, transport registration (so you can get on AIM, MSN, Yahoo!, and ICQ through JBother), sounds for different events, has several different skins, and should run on any platform that has the JRE installed (I have personally seen it working on Windows, Linux, FreeBSD, Solaris, and OS X).
See Other Best Http & Network Clients Projects in Java:
8