Aside from riding, wrenching on the bikes and cars, I like skydiving (OK- only did it once so far) and RC planes. Too many RC planes. Over twenty in the 'hangar'. Here's an old video of a 60" electric sport plane I built last year (second flight and still trimming it out):
http://www.youtube.com/watch?v=Q2YxQp_lnGQ
On board video at our flying site:
http://www.youtube.com/watch?v=mlL6JURbbac