I recall someone here integrating some kind of phone verification service. You enter your telephone number (that clunky thing with the rotary dial) and an automated call is made that includes a confirmation code. I've seen this kind of system used elsewhere, and it definitely cuts down on spam.
I think some kind of email blacklist feature would also help, though, but it wouldn't be as cool.
I think some kind of email blacklist feature would also help, though, but it wouldn't be as cool.