Laser Trip Wire
(inspired by: afrotechmods.com)
First, it's the "Where's Waldo?" of electronics. "The resistors I need are in there somewhere!"
A fine example of how not to load up a breadboard -- I didn't feel like cutting jumper wire, and I can't justify paying for it either.
It's like a little electronic city, or bug. Or city being taken over by a bug.
Some additional parts: Mirrors, Poster stuff (for applying the mirrors), and an infrared thermometer -- if it didn't appear to be working, I could check to see if the MOSFET was about to release it's magic smoke.
And don't forget the all important laser:
And there you have it, Laser Trip Wire: