Got an Arduino, a spare CD-ROM drive and an old NES lying around? How do you feel about making yourself a nifty security system out of it?
It’s not as ridiculous as it sounds, and Instructables has the ‘how-to’ guide. You’ll also need a webcam, small speaker, and a bunch of random wiring. Soon, you’ll be foiling would-be intruders with your geek skillz.