Rock and glass tumbling

I just bought myself a rock tumbler (vibratory type), some ceramic media, and an assortment of grit; something I really wanted as a young teen, but had forgotten about as an adult until recently. My first planned activity is to smash up a bunch of empty beer bottles and tumble them to get some jewelry or mosaic quality glass gems. I'd love to hear other suggestions for things to do with it though. Does anyone else use a tumbler for anything? In addition to rocks and glass I heard they can be used to clean jewelry, bullet casings, and an assortment of mold-cast objects.