I've used a Porter-Cable random orbit rotary polisher and both Maguire's and Griot's polishes to get rid of a number of scuffs and door dings in the paint. I highly recommend getting one -- makes waxing & occasional polishing unbelievably easy, like the entire car in under 45 minutes. Get a number of weights of polish and use the lightest (least abrasive) and step it up until you get rid of the scuffs, then step it back down to smooth out the surface. As you get back to the least abrasive, you'll want to wash and wax the entire car so you have a uniform surface polish/shine universally. Or, if you don't want to go to that effort, sometimes a bug/tar remover can work too, but I don't like using that stuff for anything other than just a tiny little spot.

Good luck.