Organ donation, followed by cremation. I think overblown funerals, with expensive caskets and the like, are terrible. I've seen families argue over what kind of casket to get, when all the decedent wanted was a "'plain pine box."
I'd want to have a Celebration of Life...one with good food, good music, and happy memories. That might have to be done a month or two after my actual death, though. I wouldn't mind having a second line.