I don't think just limitting submissions from one user would solve the spam problem, as spammers will create different accounts. Less naive ones will even use d

I don't think just limitting submissions from one user would solve the spam problem, as spammers will create different accounts. Less naive ones will even use different ips, change the text of the submissions while keeping the idea, and have random delays, all of this automated. But I agree it would be nice to have a better anti-spam technique, like those implemented by Akismet on wordpress.