Instructables has posted a guide for how to yank the blue diode out of a dusty Xbox 360 HD-DVD player and attach it to a (fake) gun to create.... a laser gun! It's a pretty easy little mod, if you have the equipment lying around (and a laser gun sight you don't use), and when you're done, you've got a blue laser pistol powerful enough to light a match or pop a balloon. [Instructables]
This is very, very dangerous. While I feel that many of those with the brains to put this together will realize that, there are very serious consequences for screwing with lasers like this. Please exercise caution for yourself and those around you.
Anybody that decides to play with lasers should wear goggles that block the dangerous wavelengths of the laser.
Warnings aside, [www.thinkgeek.com] sells this for $800. Sweet