I started a new project in C# using GDK.Net.
It's a control program for special effects using the Prop-2 controller available from
http://www.efx-tek.com.
The program communicates with the controller through the serial port and monitors event triggers (like a motion sensor) and activates prop events (like firing a pneumatic valve to move a prop).
The primary purpose of the program is for haunted houses at Halloween. The GDK part of the program shows a map of the "haunt" and shows the progress of the "guest" through the haunt as they trigger sensors.
It wont be ready for this Halloween, but it will be ready for next year.