Not just on the forums. There's bots loose on the Wiki too.
http://www.erfworld.com/wiki/index.php/ ... g/newusers(Jan 25, Fidofore, Grailasc, , Paloans, Nerfaye, Eaclasc, Vantcri)
Just today, three known bot accounts were set up. I banned them, their IPs, and deleted the spam. Then we got three more suspicious accounts created. I've preemptively banned them for 1 day. If it's not too hard, could be get a proper captcha in place for user creation? The simple math problem is a little too simple.
Edit: Got another one in the time it took me to write this :/