Or just create set up some Google Ads to do the hard-work for you, for a couple bucks (or free if you can get some AdWord vouchers): http://lifehacker.com/5854955/how-to-max-out-your-dropbox-re...

If I were DropBox, I wouldn't mind this one bit, they're basically getting the public to pay for their ads. Genius on both fronts :)