I use theluckylabs.com ones, they are really good. Same idea as icarbon. I don't like a case, this is the best thing for me, it offeres scratch protection for the sides and back which is all I need. I like the look too.
I used the iCarbons back on my iphone 4s and ipad 2. No complaints here. They work well (I never had any issues with them fitting, staying on or coming off) and I like the pseudo carbon fiber texture. I'll probably end up putting one on my 5 when I get it in October.