Here's a really interesting video on how to make a 245mW laser using nothing else than a DVD burner, and a flashlight. At 245mW it can light matches and pop balloons pretty easy, so be careful if you decide to do it at home!

This little submachine gun cleverly disguises itself as a flashlight and can be stashed in your back pocket as needed. At the first sign of danger, you can unfold it and use it as needed. Really clever stuff!