What store has cool replacement back housing designs/colors for iPhone?

I have to replace the battery on my 3GS and figure I may as well replace the plastic back housing since it is cracked. I’m having trouble finding much in the way of my kind of cool (adult male who doesn’t want kittens on his phone). Do you know of a source? I looked at some site called “Trait something” but their designs seem lame. I also looked on Amazon, which has some colors at least that are better than nothing. Any help?