Lego Mindstorms + Lasers
hamsan writes "My brother just hacked a laser pointer into an NXT light sensor and fully documented the process. From the page — 'Total Project Cost — $16.99 plus shipping. Time Required — Approximately 2 hours of tinkering. Having an Alpha Rex with a Laser — Priceless!' Of course, the usual warnings about voiding warranties and avoiding lasers apply."
http://www.networkmirror.com/e_zi0XdE7_2rIRat/www. kevincook.net/NXTHack/index.htm
"I'd rather be a lightning rod than a seismometer." -Ken Kesey