Captchas and anti-spam Gems

#Total RankDaily RankNameSummary
1778826recaptchaHelpers for the reCAPTCHA API
22,4962,993voight_kampffVoight-Kampff detects bots, spiders, crawlers and replicants
32,719735invisible_captchaUnobtrusive, flexible and simple spam protection for Rails applications using honeypot ...
43,2035,683rakismetRakismet is the easiest way to integrate Akismet or TypePad's AntiSpam into your Rails ...