Nounours is a Javascript Web client to Jabber protocol. It's using BOSH implementation to communicate with a jabber server.
Psi+ is a cross-platform powerful Jabber client (Qt, C++) designed for the Jabber power users.
psyced, a scalable multi-protocol multi-casting chat, messaging and social server solution to build decentralized chat networks upon, released as open source.
real time social browsing - With the SamePlace extension for Firefox, you can enter a virtual place associated with each web page you visit, and meet others who did the same. realised with jabber
TrophyIM is a Jabber (XMPP) client built on top of strophe