just got my atrix and otterbox commuter! the commuter works and i highly recommend it. not bulky whatsoever IMHO. both my brother and girlfriend have iphones with OB defender cases and the bulk is insane. i decided to go commuter and i love it.
Another recommendation for the Otterbox commuter. I have a BestScreenEver skin on the display and the commuter on. The hard shell works well for pocket use and provides enough protection for my day to day use.
I originally got the Otterbox Defender, but the first one didn't even close, and on the exchange, I realized that I didn't like the Defender: The screen felt like I had to push it ala Blackberry Storm, so instead I got the Speck Candyshell with the ATT Store's screen protector. Amazing, looks, feels, and most importantly, protects it great.
I just found these from Brando. They probably don't do much for protection but they look really cool. I bought one for my Atrix and one for my iPod Touch.
I just got a case made by Trident it has a built in screen protector an inner soft rubber cover and an our had cover and a kickstand and it came with a holster clip I think it fits better an looks better than an otterbox