Depends how deep they are i guess. I have loads running down my car doors, and in the 4 months i have had it no less than 3 people have rolled backwards into it. I think the next time it happens i might be on a murder charge.
There are a few PDR (paintless dent repair) companies about - dent devils etc & many local indies. They usually charge about £40 per panel. They can only work on the dent if they can get to it & the paint is still intact.
It seems every time I park in a well known supermarket car park I get a new ding - have been known to take 1 & 1/2 spaces to combat this
I don't shop in asda because it is cheap and the whole credit crunch thing, but because they have some spaces where no one can park either side of you. Someone though I have still picked up two door dings, annoyingly I think when the car is left at home