The sweet spot for the magnet is on the back somewhere... I haven't experimented to figure out where exactly, but I know it's on the back because if I set my storm down face-up on top of my OEM sleeve case (with the back against the case), my storm goes into sleep mode.
I use a full InvisibleShield by ZAGG and slip it into the OEM sleeve like the one FBuzin mentioned so that I can carry it in my back pocket -- I'm not a holster/belt clip guy.
I would definitely recommend the InvisibleShield (or something similar -- I loved the BodyGuardz I used on my last BB) above all else. By far my #1 accessory for protecting my devices, and makes for fantastic resell value!