Darth Avlectus

If it's possible he knows where you live, get a gun. Shotguns are easy to get in most states (usually a 24 hour waiting period for those eligible to purchase). I'd go for a Remington 870 Express. 18-inch barrel with a 6-round capacity. I've got one, and I love it.

That may be taking it pretty far, but it's better to have something and not need it than to need something and not have it. Plus, guns are fun.

If he's sent you any messages on any forums or websites, forward them to the mods. Save them to possibly present to the authorities if he gets really serious.