I ended up going with an iSkin Revo for my iPhone as a thin little protective case, but now that I've seen some of these crazy cases, I'm reconsidering just a little bit. Who wouldn't want to encase your iPhone in what appears to be bacon, or try out the tactile iPhone case above (which transmits button presses to a customized home screen -- not something I'd want to use all the time, but it is wild and it has a purpose).
That Dexter case is cool too, though there are probably plenty of promotional cases out there. It's almost too bad -- when I picked up my plain black case, I was thinking a lot more about function than appearance. There's all kinds of cool things out there to put your iPhone in.