STM makes some of the best iPad-specific bags we've come across, and its new Stash Shoulder Bag for iPad + iPad 2 ($55) lives up to the company's reputation. Made of high-quality, water-resistant ripstop polyester, it feels and looks very nice. There are a number of pockets, including one main compartment for your tablet, and smaller ones for accessories. The bag can be carried one of two ways: there's a detachable shoulder strap, as well as handles…