The Zagg skin is different in that if it gets a scratch, somehow in about 24 hours, it actually heals itself. Kind of amazing really. It's a little pricey, but considering it leaves the screen crystal clear and protects like a full case, while still allowing you to use in docks, makes it worthwhile.
If anyone is looking for a different kind of screen protector and doesn't like the feel of Zagg, I've been using Steinheil Crystal on my Droid Incredible and iPod Touch. The only thing that sucks about it is that it doesn't have the "self healing" quality that the Zagg does, but feels VERY similar to the real glass and gives an excellent appearance when applied. You really can't tell it's there. It also used static instead of adhesive to apply to the screen so if you change your mind, it's easier to remove and clean up.
Will BestBuy install it even if I purchase one on their website?