Keep this in mind during and after the scramble. There are some PDs who do not advertise their vacancies, for whatever reason.
One guy in our med school didn't get a prelim spot in the match, and he failed to scramble. A few weeks later he sent out about a hundred emails to various PDs, asking them if they had openings. He got several interviews and eventually went to a great prelim year at a program that said they were 100% filled in the match. It was a better program than the ones he had interviewed at!
As a matter of fact, several people in our program didn't match, but by June all but one had found residencies - great spots, too.
I also used this to my own advantage when changing residencies.
If for some reason you can't scramble into a place you like, don't give up hope. Call all your buddies, use your contacts, find the hidden job market. It's out there.