Gamefaqs.com has a system of Karma that is very good. If you put one in that was stricter, you'd be set. And I know the current board system doesn't allow for that, but I'd gladly donate my spare time (and I have quite a bit) to building this.
It could drastically change the system.
Check this out:
Little Timmy signs up for the KL forums.
He signs up as b1ggayhax0r.
Then he thinks "what trouble can I cause?"
Sadly, he has to WAIT 72 hours (3 days) if he used a freebie email account, and 24 hours if he used a paid account or one from an ISP.
Accounts from freebie email addies can only post 2 topics per day, and can only post 5 replies per day.
Accounts from paid email addies can only post 5 topics per day, and can only post 7 replies per day.
After the timeout periods, if the email addy was verified, the account has limited usage until 150 posts.
If it wasn't verified, the account is shut down and deleted from the db along with all posts/topics made.
If another signup is attempted, and the address still cannot be verified, the ip is banned, along with the name and other useful thingies.
Also, limited users cannot post as many replies on their own topics as on other peoples.
Until 50 posts, you're limited to a cap of 25 posts a week.
From 50 to 100 posts, you're limited to a cap of 50 posts a week.
From 100-150, you're limited to a cap of 75 posts a week.
From 150 and onwards, you're free as a bird.
And if you pay a one time fee of 10 bucks or whatever, you can of course have limits removed immediatly.
Tell me what you think. I'll start to design it immeditely if you want.