I bought one of these recently, they are the biz. I bought a black one as I have the 80gb in black. It came with two crystal clear backs for the 80gb and 160gb.
It protects both the screen and the click wheel. The protection for the click wheel is a thin plastic thing and very sensitive, so you don't have to worry about scratching your ipod. I have bought some cheap ones and they do not compare to this one, the quality is not as good. Also Play's price is the cheapest around under a tenner.