I switch between an AMK Field Kit and .5 Ultralite kit, depending on the size of group I'm with and what we're doing.

The Field Kit (I don't see it on their site anymore. They've got a Field Trauma Kit which looks bigger) is a great small-sized pocket kit. I've refilled mine with a variety of bandaids, steri-srtips, prep pads, polysporin, some gauze pads, a thin maxi pad and a fauxton.