Invisible Shield - I Second that! I saw a few videos of that and it's impressive. It protects the front, sides, screen, and back. All without the bulk. It has a hefty price tag, but think about it, a good ipod case at the store is like 20 bucks, this protects your device just as well. I just ordered mine, hope I get it before my ipod though, that is gonna be the first thing I do is put that on!
The best part is the lifetime warranty, which is in fact, legit. My friend has one and I dunno what happened to his cover, but it started peeling all the time, so he called them and they sent him a new thing, for the whole device! For free I might add.
I have used a ton of difference cases for my ipod and by far the best one I have ever used is the iClear case, but in the past I always used this type of cling wrap that protected the whole thing, but I would have to put on a new one every week. But it was the best cuz it didn't add any bulk.