It's clear that there are a lot of Star Wars fans these days, but one of them just took that adoration to a decidedly geeky new level. Styropyro (he of laser shotgun fame) has built a lightsaber using a heavily upgraded 7W blue laser -- it's several times more powerful than what's needed to blind someone. While the beam isn't contained like the "real" thing, it's strong enough that it can burn through wire and other household objects. You probably don't want to build this at home unless you're exceptionally careful, then.
And don't worry if 7W doesn't sound impressive. Styropyro is teasing progress on a laser bazooka that would combine multiple 40W lasers. It won't be nearly as portable as the lightsaber, but it could put on an even bigger show.