Zome is a nerd toy that allows you create all sorts of amazing polyhedral models. Some people are more serious about them than others.
Addendum: A couple of days ago, I picked up one of those generic "ball bearing and magnet" sets that allow you to build similar structures at Walgreens. It was $9.99 for a 250 piece set, which seemed pretty good. I assembled a stellated icosahedron, but I don't really recommend the set: the magnets are incredibly weak, and it's almost impossible to move the model without destroying it.