Skt NURCaptcha Plugin now brings your WordPress site to a new level of security.
From version 3 on, we added antispam databases assessment, so even if the spammer gets the spambot gone through Google’s reCAPTCHA challenge, the IP and email will be checked against StopForumSpam and BotScout spammer databases.
This additional checking became a real need since some spammers found some way to cross the captcha barrier, a few months ago. They are probably using a cross-site game, by making someone else unadvertedly solve the captcha challenge for them.
Version 3.1 also changed storage of blocked attemptives from text file mode to database mode, so there will be no more data loss at the plugin update.