Model rockets rock. I have a home-made relay launcher right here I built for the big ones.. G-J... but I like chad staging C's (taping a booster stage motor to the bottom of a single stage) when I get bored...
Rocketry is pretty darn fun, but too expensive these days...
Water rocketry is pretty cool too. Built a two stage rocket out of 16 1 liter bottles, launched it from a PVC launcher with a bike pump, pumped to 120PSI. It went about 300 feet, dropped the stage, and continued to about 1200 feet, recovered by parachute.
Tried a 2nd launch and it exploded on the pad. Scared the crap out of me and the police officer watching me
ops:
I packed it up for the day... soaking wet...