An XMPP BOSH connection manager, written in Ruby with EventMachine and usable as both a standalone connection manager and as part of a rack app (at least with Thin). Currently in an alpha-ish state. Has been used in a fair amount of testing, but not in production. ChessFlock (http://github.com/s...

Ad-hoc service discovery and routing for DNS-SD (aka Bonjour) and XMPP.

Building XMPP clients should be easy.

Babylon is a framework to create EventMachine based XMPP External Components in Ruby.

Tools for consuming Fire Eagle's XMPP PubSub feed.

Rollcall plugin for integration with the Prosody XMPP server

An XMPP bot for Vanderbilt Biostatistics

wcc tracks changes of websites and notifies you by email and as of version 2.0 via XMPP/Jabber too.