A semantic agent for xmpp / jabber network which finds and shares content about resources (using RDF/SPARQL) for you and your jabber friends.
An ajax web jabber client
Psi+ is a cross-platform powerful Jabber client (Qt, C++) designed for the Jabber power users.
A simple, open, server-to-server web-hook-based pubsub (publish/subscribe) protocol as an extension to Atom. Parties (servers) speaking the PubSubHubbub protocol can get near-instant notifications (via webhook callbacks) when a topic (Atom URL) they're interested in is updated.