Then there's the old "Brag Flag" idea. I'm all for that, as it looks cool on the boat between race days.
After the Machoman Ding strung up his collection of burgees - there had to be 30-40 of them and I thought that looked pretty impressive.

How about having a deal set up with a printer where the winners/entrants could choose between several items - shirts, hats, boxers, etc... Just ask what they prefer at registration and either give them out locally or include the shipping costs so the printer can ship them out directly. Once the printer has the design in the computer it should be easy enough for them to do.