I use a Camelbak bag with several pockets. I carry a Point and shoot digital camera, swag, tweezers, pens, pencils (mechanical), Paper, logs, Geocaching pamplets for muggles, flashlight(s), batteries, and my GPSr. As I cache more I find I add what I need more and more. I am sure as the years go on it will change. I tend to trade less and less often and just find caches now.
I really like the idea of a mirror that someone else said as well as the magnetic wand...