Adding a new case, just went over to Best Buy to test out some cases for my new N900, and came across a belt case (horizontal) for HTC. Item# 82024LRP

It has a nice suede/type material inside that holds the N900 snugly, and the magnetic flap closes well. The sides do block the headphone jack IF you put it in right side up, flip the N900 over and the headphone jack is accessible.