What's the best downhill safe fall if you're getting a lot of speed wobble, or you're on a really rocky course and lose control?

I noticed a lot of people try to slide the bike down to its side, but that isn't always possible. When it's not possible to do that, should the bicycler try to pop a wheelie and go to his back? Jump up and start running, and then slide on his nostrils? Roll? Log roll? I've seen so many different falls, and I've always improvised. I'm of the belief that you have to know how to fall before you do any sport, though, and I don't feel right not having researched bicycling safe falls.