Synergy ( http://synergy2.sf.net ) with Zeroconf support.
The Zeroconf implementation is currently based on Avahi. The Zeroconf implementation at all is quite abstract and allows further implementation beside Avahi - e.g. Bonjour.
Additionally synergy get enhanced to support "multi-homing".
Use case: Allow a laptop to act in different roles (client/server) depending on the environment/network (home/office).