Handy LPT port pins manager (also support COM port via USB)
Building automation (like KNX or OpenHAB) software (like CometVisu).
Library for controling Vellman K8090 USB relay card under Linux
Alternate Insteon implementation for Vera home automation controller
Fronius data tool for Linux
Software for the placement of removable devices shortcuts.
Use your arduino to control remote controlled sockets by SMJ.
Brewing System Automation Controller
a wake on LAN/wake on WAN packet generator.
send and receive artnet / art-net, more than DMX over ethernet network