I don't hit the ground too much but with all the riding I do it's bound to happen from time to time. The potentially worst crash I ever had was when a friend in front of me in a paceline touched wheels with another friend and took me out. Very painful but no lasting injuries, despite the high speed. Tegaderm brought new skin to the road rashed spots, great stuff.

I've also been hit by cars a few times and walked away with barely a scratch. That hasn't happened in a long, long time (older and wiser?).

Worst crash in terms of lasting effects was the result of a dooring which I almost certainly wrote about here some five years ago or so. My elbow still aches a little sometimes after presumably being sprained.

While technically under the Queensboro Bridge as part of my approach to get on it, less than a year ago IIRC, I hit the pavement. It's a shoddy bit of sidewalk that always seems to have some dirt on it and requires a right turn to get to the proper bridge path entrance. I was preparing for the right turn when someone coming off the bridge came around the corner the other way and for some reason this one time whatever automatic, small adjustment I made in my trajectory sent me into a skid which I very nearly stopped by unclipping and dragging my right foot. In the end I came to more or less a stop and plopped down on my rump. No real harm to me or the bike or even my bike shorts.