What is this mess of nylon, straps, and Velcro? It's the iPad Shoulder Holster ($40) from Tablet Holster. That's right, an iPad holster -- as in, someone expects that you'll wear this and pull your iPad from your side like a gunslinger. The main component is a ripstop nylon pocket that's not tailored to any particular model of product -- either generation of iPad will fit, even with a case on, and still have lots of room to move around. A mind-boggling…