Well one of my big interest is Geology.  Don't groan before you actually have a really good look into it.  Wasn't much into it myself until I took a coarse in college and before I knew it I minored in it.  Really is fun to be able to walk along the road and actually be able to tell what type of rock it is you are walking on.

Judo is another one of my hobbies.  Unfortunately there isn't a club near my home town so I'm stuck not getting to practice right now.