Google recently announced its holding a contest for budding videographers that will send the winner to the 2008 Democratic or Republican national conventions. All you have to do is submit a video depicting a day in the life of the candidate you support. From the Official Google Blog:
Through unprecedented partnerships with both the Democratic and Republican National Conventions, we just debuted a video contest that will send one talented winner from each side of the aisle onto their candidate's campaign trail, and ultimately into their party's national convention in Denver or Minneapolis-St. Paul. The call to action is simple: submit a video explaining why you're a Democrat or Republican in 2008. The five most compelling and creative videos selected by each convention will be voted on by the YouTube community, who will determine the final winner.
Details are here.
For associations, why not dip your toes in that YouTube pool? I don't know what your contest could be, but I'm sure you can think of something.