If you have a GPS device and want to track the device on real-time basis on a map, Web GPS Tracker will allow you to do this. It is a quick and dirty (but working) application.
runasdog (run as watchdog) is a tool that connects STDIO of any program to a listening TCP socket.
Tardis is a TimeMachine style backup system for Linux. It provides incremental versioned backups, filesystem-oriented recovery, and encrypted backups.
XBMC Blastdav is a simple WebDAV-like server for streaming content to XBMC. It works through proxies and tunnels, and even streams smoothly from a Raspberry Pi.
Access to UDP multicast streams via RTSP/RTP unicast protocols.
A advanced event querying engine.