http://spamcop.net
Regular use cut me down from 25 a day to 25 a week.
And the only means to truely whack spam is at the mail server using blacklists which reject messages from certain IP's.
True, the method WILL reject valid and legit emails because the legit is being served from the same ISP that a spammer uses, kinda like the post office refusing to pickup mail from a certain city because of junk mail, but a blacklist will work constantly and consistantly.