So of course if you're a true obsessive you can't merely have one, so naturally I have a second: lampworking!
For anyone unfamiliar, lampworking is the art of making glass beads with a torch. You can see the results here, particularly if you surf around a bit:
I'm a complete newbie at this, so I'm nowhere near as talented as these fine folks, but I hope to grow up to be like them someday.
I'll post some pics of my beads soon, but that's another thing that takes up hours of my time... that and stringing the lovely thousands of beads that I already own. =) (No, I'm not kidding; I have quite the collection!)