Depending how evil you are you can follow the Facebook-app model of offering the personality tests, games and whatnot for free and then getting them to sign up to get the results - only let them know that they need to sign up at the end though.

This coupled with a minimal info request - name, age, email, location (at first) should hook you some punters.

Indeed a FB app is probably a good seed method (or would have been last year!) - something like "which of your friends is most compatible with you" ... you can snag extra info about them under the guise of refining the friend choice then at the end say "here's a list of people [not their friends other people near them] who might want to date you, get more dating suggestions by signing up".

I've thought of using an FB app, but like you said - last year it would have been great: last year; instead of a quiz, some sort of game that collects the needed info peripherally might work (full disclosures in the game, to lessen the evilness of course)

I would be much more likely to sign up if I was told in advance. I don't like to be strung along and tricked.