enigma1 - 7:44 pm on Mar 24, 2012 (gmt 0)
You would have to put some code to rule out the bot factor at least. Both for account registration and post submission. It will ease moderation.
Some basic ways are by using js, session renew and button click verifications so the forms are submitted only by a human. And there are way even with CSS to protect the forms like using a number of invisible buttons surrounding the form one of which is visible and active. Bots cannot tell the difference and automated submission will fail.
For the manual spam submission you could have some code to make any hard link posted into a js wrapper (spiders could not see) so spammers have no incentive messing with your forum.