I'm a special events volunteer with the Jimmy Fund (one of the preeminent cancer hospitals in the country here in Boston). I run phone banks during their radio telethon, and help out at the Scooper Bowl (all you can eat ice cream event) and Fantasy Day at Fenway (fans can pay to go onto the field at Fenway Park and hit, field, run the bases, etc).
I also am the Registrar for our Town's soccer club. DS lives for soccer, and since I'm too much of a klutz to actually coach, I volunteered to help administrate.