Out of curiosity I stopped at a Verizon store and tried a DROID X case with my Droid & Otterbox and it fit. But the Droid X case had a magnet which turned my phone on. The case was the official Motorola Droid X leather pouch and had a belt clip.
If there was no magnet I would have bought it. Maybe once Droid X accessories we might be able to find something.