http://www.stopforumspam.com/

This site was created to be used as a central database for known forum spambots. It should prove useful to the administrator of an online forum when trying to find information about questionable registrations.

Currently (ATM) they have information on 546061 spammers since about December 2006. Enter an IP address, email address, or username to search. The list is updated every five minutes. This is useful for confirming false forum registrations, banning IPs, emails, and usernames.

There is a mod for phpBB3 that is constantly connected to their spambot database and blocks any and all entries known to be a spambot. I recommend it!

Finally a reason to upgrade to phpBB3...

Although, we don't get much spam here with the mods in place nowadays.

Do you have a link to the mod for phpbb3?