Some pet projects I did over the years:

• Ultimate Foosball. New rules for the game of foosball. It makes the game much more exciting. Trust me. :) Download the academic paper describing the rules here.
• Dartboard IP. This project involved hacking an electronic dartboard and connecting it to a PC through a parallel port. The PC relays dart hits over the internet to a graphical game interface. The client interface looks identical to the dartboard so it can be projected onto the dartboard itself to add to the experience. (Appeared on slashdot.org on February 2002, resulted in over 50,000 web page hits in one day.)