I've added code to this forum that will compare a registered users username, email and ip address against an online repository of reported spammers and enforce a ban. This will also effect anonymous users based on their selected username and IP.
This is kind of experimental so there's a risk this may spoil some individuals experience, either because they have been falsely identified, or because I've made a mistake in the programming logic.
A ban triggered by an offending username or IP is only temporary whilst a ban by e-mail address will be permanent. I'll be monitoring the logs to see how the bannings are going.
If you find you've been banned without cause, please post anonymously in the Registration issues and website problems forum (remember an anonymous ban should only be temporary and you'll be informed how long the ban is for).