The best way to combat this is at the network or firewall level. You could also try the “human test” plugin by _ck_ which may discourage them for a while.
The spammers figured out how to defeat the old Human Test so I updated it:
and I will be updating it again later this month to make it even harder
I’m forcing all registrations through my blog; will this plugin work in WP?
Yep same here, big increase in spam regos this week. Thanks _ck_ for the update, I have installed the new one and will keep my eye out for the newer version still.
@mzimmers – no, it will not work with WordPress; it’s a bbPress plugin. There are other plugins available for WordPress, but only this one for bbPress as far as I know.