I won a $5 Amazon Gift Certificate on Blingo! This was my first Blingo win in ages! Blingo is basically a Google-powered search engine, with random prizes during searches (and it has a Firefox search bar plug in, so I pretty much just use it in lieu of Google for basic reference searches). If you sign up via my link and then win a prize, I win one too.
I also use Winzy, which works the same way, but uses Ask instead of Google (alas), and which also has monthly sweepstakes. WInzy is open to Canadians and folks in the UK (Blingo isn't). Haven't won a prize (other than Winzy Points, which convert to sweepstakes entries) there in a while, but I've gotten gift certificates there, as well.
I also use Winzy, which works the same way, but uses Ask instead of Google (alas), and which also has monthly sweepstakes. WInzy is open to Canadians and folks in the UK (Blingo isn't). Haven't won a prize (other than Winzy Points, which convert to sweepstakes entries) there in a while, but I've gotten gift certificates there, as well.