I score 8. I can do everything except the palms flat on the floor with knees unbent one. Most of that's because I'm overweight at the moment – when I used to be a hockey goalie I could do that pretty easily as well.
That said, the elbows and knees aren't seriously pronounced -- I can't bend in completely the wrong direction.
Sorry this is a little late to reply, hadn't been by in a while…
@Jointcracker, you're of course right that RSI == Repetitive Strain Injury, but when I said CPS, I actually meant Carpal Tunnel Syndrome. I'm an unlucky IT worker afflicted with both problems that make it hard to type 
I went to the chiropractor regularly for about 6 months. To be clear, I was seriously damaged after my accident and a lot of "bad healing" (things healing in the incorrect place, damaged muscles strengthening without healing etc) needed to be undone. As another poster has said, at first it was just a cycle of short-term relief following by major pain, but I stuck with it and came out the end of it feeling MUCH MUCH better.
I don't need to see a chiropractor any more, especially if I crack the joints myself and make sure to exercise regularly. In particular I find weight training helps a lot. That said, I do go back a couple of times a year, usually when I've been travelling for work a lot. Flights on cramped planes sure can f**k you up!
I had a really bad motorcycle accident a few years ago. After that, I started getting really bad headaches and also my RSI/CPS started getting much much worse.
When it got to the point when I really couldn't even write for more than about 10 mins because the RSI had gotten so bad, my GP referred me to a chiropractor.
At first it was just really scary – the chiropractor cracked all manner of things I hadn't even realised should be able to move! He figured that most of my problems were because my back had healed incompletely after my bike accident. But I immediately had some relief from the pain and started to think perhaps it would help. He also used ultrasound and accupuncture on my worst affected muscles and that really helped to. After a course of treatment I was sorted!
Up until then I'd only regularly been able to crack my fingers, wrists, ankles, knees and hips. The chiropractic treatment must have helped with some stuff, because my back and neck and chest and arms are now able to crack -- whether it's good for me or not It's all much looser, my RSI is under control again and the tension headaches are virtually gone 
I'm a big advocate of chiropractic now, as you might have noticed
I can and have cracked my elbows, but I must admit it's not one of my favourites! It's more a disturbing feeling than relief…
My hips crack ALL the time. It is quite a good sensation, but sometimes it worries me because it's VERY loud
I found that when I lost a lot of weight my back pain got MUCH better. I also found that weight training with a focus on the back muscles helped massively – just exercising those muscles specifically seemed to do a lot to help it.
If when you've lost the majority of the weight you're still having problems, might be worth chatting to your doctor. Often a chiropractor can help if you displaced something or slipped a disc
Firstly, of course, I can't RECOMMEND any of the things I'm going to mention below – at your own risk, etc etc. But they sure as h**l work
The best way I've found to crack my back involves help from someone else. I lie on the bed, with my head over the corner and arms down either side of the corner. Then I get my gf to place her hands on either side of my spine (pointing out from the spine) and slowly push directly down -- there's a lovely cracking/clicking noise and then the vertebra is back in the right place. Repeat for the entire spine.
I also find that if I roll my shoulders back and then try to push them together (like trying to unfurl wings), then I get satisfying cracks from my upper back.
During long meetings, I've also found that the chairs we have at work are at just the right point on my back that if I just lean back it all cracks.
If you've NEVER been able to get your back to crack, then it's possible that everything is just held in place too strongly. I got to that point after a bad motorcycle accident -- my muscles were semi-permanently tensed and holding the spine slightly wrong. I went to a chiropractor and now it's all much looser and cracks dead easy