I keep my DX in a M-Edge Platform Jacket (I got the black genuine leather one):
http://www.medgestore.com/products/k...x-platform.psp. It offers great protection. I haven't used the platform feature too many times, but I like that when I fold back the top flap (which folds back completely flush) it creates a perfectly uniform reading surface. I would imagine that with some book-style jackets (open left to right), when opened and folded back flushed would make the DX more propped up on the left side than the other... you know what I mean?
Only drawback I see to the M-Edge case is that it is rather heavy. This isn't a big deal to me as this shows how much protection you are getting from it. You can easily slide the DX out of the case if you are going to read for a long period of time, and then slide it back in when you are done. Also, the case comes with a busines card holder in the underside of the top flap. I was afraid that the edges of this holder were going to leave a mark on the screen of the DX so I removed it (took 5 minutes).