Has anyone seen a good replacement back for the iPhone 4 made of that rubbery "soft touch" material? I'm referring to the type of backing that the kindle 3 or the droid incredible has. I've replaced the back of my iPhone 4 with an aluminum back (from an obscure chineese website) in the past, and I've seen wooden backs for sale, but that soft touch material would be great for grip and wouldn't be scratch prone. So far, I haven't come across anything like this, just wondered if anyone had seen one. Thanks!