Captchas and anti-spam Gems

#Total RankDaily RankNameSummary
1753866recaptchaHelpers for the reCAPTCHA API
22,4842,413voight_kampffVoight-Kampff detects bots, spiders, crawlers and replicants
33,1434,028rakismetRakismet is the easiest way to integrate Akismet or TypePad's AntiSpam into your Rails ...
44,0822,918invisible_captchaUnobtrusive, flexible and simple spam protection for Rails applications using honeypot ...