I have a suggestion on how to curb spammers.
Let people sign up and post right away, do away with the email verification and all that. But make a script that reads the first (or first 3) post(s) and if there is a hyperlink in the first post or maybe the phrase "www.,"".com," ".net," etc, the system will automatically suspend or "quarantine" that member until you can verify that it's not a spammer.
That is pure genius.