Glad you're alright.

I don't get it though. How did he collide with you if he was stationary? Rolled down a slope?

Must have been sitting with his foot on the clutch.

As Mark says, glad you're OK. Car crashes - even minor, injury-free ones - are scary.

I don't really get it either, to be honest. He started moving again, obviously, but I have little idea why. Maybe it was an automatic and he took his foot off the brake; that or he eased his foot off the clutch for some reason. Either way, he wasn't watching what he was doing. When I looked in the rearview, he looked up, as surprised as I was by the impact; he had been looking down, doing something with something in the car.

That happened to me a few years ago on the way back from a Radiohead gig. Sitting at lights, handbrake on, and couldn't do anything but watch as a bloke in a Cavalier scudded into the back of me at 40mph. He only realised I was/traffic lights were there immediately before he learned a valuable lesson: if you hit the back of a Saab at 40mph, your Cavalier will lose.

I'm glad you're alright (and even though he might have been a dick, I'm glad he is alright, too). Having been both responsible for, and the victim of, a few minor skirmishes like that over the years, I think it WILL shake him up and make him more careful (at least for a few months, but that's better than not at all).
My pet hate is what Americans call "tail-gaters" (those pr**ks who drive about one foot behind you on national speed-limit roads). In my head I've "designed" two stickers which I wish were available to put on my rear window: One says "the closer you get, the slower I'll drive. Wanna go at 60mph? BACK OFF NOW!" The second says "You're either gay, or else you are trying to ram yourself up my rear end for reasons totally unknown to me. Either way, if you can read this, the future of your no claims bonus depends entirely on the whimsical movement of my right foot, you total wanker".

You'd need a pretty wide bumper for that last one.

Or, upon reflection, quite teeny writing.

Would it be illegal to have a switch on your dashboard which would illuminate your brakelights without your using the brakes? Just a thought.

You mean like the foglights' switch? That's what I use.

Wire in the backup lights, too - that really gets their attention.