What to do if you are about to get doored?
Personally what I'd try to do if I saw it happening and had the split second decision making ability, would be start leaning toward the car (assuming the door was open enough) so that I'd end up slowing down by sliding against the side of the car and keeping any part of my body away from the sharp corner/edge of the door. If a passenger was getting out I'd use that body as a cushion, if not I'd try to get myself to go over the door frame as close to the hinge point as possible to avoid upper body injuries at impact though they may be sustained going over the door frame. This all assumes the door is more open than not.

Another thing you should do is practice a Quick Stop so that it's second nature when necessary. This is a technique where you get up off the saddle and get your ass behind the seat and even lower than the seat. The idea is to get as much weight over the rear of the bike as possible and then light up your front brake (this needs to be one fluid/fast motion). If done right, you won't endo. I've been able to skid my front wheel (not ideal, doesn't stop as fast as a rolling braked wheel), but skidding a front wheel is not an easy task and shows just how much weight you need over the rear of the bike. A Quick Stop really is a very quick stop.

The best thing you can do is ride left and watch for ANY movement inside parked cars, if you see any, either slow or go further left if safe to do so. If you're going the speed limit, take the lane and skip the bike lane entirely if it's a bike lane that's left of parallel parking.