Cub scout Den Leader - Really makes a difference cause I have a few boys whose dad isn't really around, and I get to be their male role model.
Numismatics - Expensive as hell, but can be done on a cheaper scale. I started out broad and have narrowed my focus to Mexican coinage of the first and second republic from a specific mint. The research into it may eventually lead to a book, as virtually no reference material exists at the moment. There is something pretty cool in holding a coin that is a few hundred years old and imagining who held it, the stories it could tell, and viewing the art associated with it.
Crossfit / Olympic Lifting. I started Crossfit, I found I enjoyed it but really sucked at the olympic lifting. Then my box started a class specific on the fundamentals of olympic lifting, now I'm hooked on both. It's good to get out from behind the desk, move and jump and lift. It can be bad though, I've seen bad boxes where one can hurt themselves easily. It really comes down to the coaches and you making smart decisions.
Finally Wood working - I love creating furniture most of all and am at the point where my extended family have started asking me to make furniture pieces for them. There is something about starting out with several pieces of wood and ending up with a finished product that you've made with your own hands... Although I can point out every flaw in every piece I've ever created!