We are using the Anti Spam solution from www.cleantalk.org, and its working great! Since the CleanTalk Anti-Spam plugin was enabled, there have been 0 fake registrations trought bots or spamers.
CleanTalk uses a blacklist database that is constantly updated by every CleanTalk plugin user, and is very quick to recognize new spamer IPs and E-Mails.
So if you need a reliable Anti-Spam solution for your Forum, E-Commerce or Wordpress - check out www.cleantalk.org and make your life easier without spamers hasseling you!