If you've noticed a sudden trend of bots registering via FaceBook/Google/Twitter, then like me you want to stop it quickly.
The FaceBook/Google/Twitter registration page is often neglected by many spam prevention techniques, making it an easy target for bots.
This free plug-in simply adds your current CAPTCHA mechanism to the FaceBook/Google/Twitter Registration page.
I recommend to use this with [TAC] Custom Image Captcha, but it is your choice to use this with your preferred CAPTCHA mechanism (keyCAPTCHA / are you human / etc).
This should work with any CAPTCHA mechanism, and simply turns on the CAPTCHA mechanism for FaceBook/Google/Twitter Registrations.