The NuGuard KX offers strong drop protection without a lot of bulk. OWC describes it as hyper advanced x-orbing gel to buffer the iPhone. Tests have been made from the top of a wind generator on to the ground and up to 20-foot drop on concrete. It also offers a lifetime warranty.
The NuGuard KX is expected to ship in about a week for the iPhone 4/4S and iPhone 5. It's expected to have a retail price of around $35.