This was posted on the DoridX forums to generate some interest. I always wanted one for my Droid 1, but hope they make it for the Droid X. To see what exactly it is, you can see it here for the iPhone and here for the Blackberry Tour.
What it is, is basically a casing for the phone that allows a few cards to slip right into the back of the phone. Whether its your license, credit cards, metro cards identification cards, etc.
So, if anyone is interested in this type of case, vote for it here! to generate some interest.