Technical certifications/Computer technology - my job.
Scuba Diving - my hobby.
Computer Gaming - my total distraction. Makes my wife hate my computer. Course, not as much time as I had when I was younger. With a baby on the way, I guess something's gonna have to give.
Chemistry, but only because I majored in it. Never used it for a "job".
Physics, but only because I minored in it. I guess I'm past "most people", but not "most physicists" or "most chemists".
Course, there's ALWAYS someone that knows more than you do about any particular topic.
I used to know a lot about RPGs (role playing games), but I've slacked the past few years. I used to know a lot about Magic: the Gathering, but I haven't collected in years. That should be a thread: What did you used to know more about than other people, but have forgotten or fallen behind in learning?