CYCLING is a big one (actually, this is a lifestyle more than a hobby), art, RC models (though I've not done this one for a bit), history, basketball, being a spectator of just about any college sport, collecting and cutting rocks and gems, wine tasting and collecting, trying to follow anything Aerospace related, SpongeBob Squarepants, and studying the migration patterns of the Mexican Free-tail Bat. Of course the kids have curtailed much of the above, except for maybe SpongeBob!
As of late, I've also enjoyed watching Reefugee do his hobbies!