try something like this (att.: resizes window) -> http://www.staples.de/DEU/Catalog/cat_detail.asp?webid=A0854
transparent, cheap, durable ... i'm not kidding, it works great.
one roll of this lasts for about a hundred ipods.
I put my Palm's screen protector on the back of my iTouch. since iTouch's back actually less endurable then front... how strange.