Hey.
As you certainly have noticed the spambots are quite active here on the board.
The phpbb3 3.0.4 captcha has been cracked which makes the life for spambots soo much simplier then normally.
Tho its not the case on all boards, I just had the very first spambot successfully registrating last night, tho it didnt succeed on posting anything (guessing it was a human spambot).
What captcha settings are you guys running?
(increase the visual difficulty)
Add some custom profile fields. (Atleast one thats required and make sure the one autopicked isnt allowed as answer).
Thats some basic stuff, visit
http://www.phpbb.com for more information.