After an hour of cleaning up comment spam, I’ve installed reCAPTCHA. From the website:
A CAPTCHA is a program that can tell whether its user is a human or a computer. You’ve probably seen them — colorful images with distorted text at the bottom of Web registration forms. CAPTCHAs are used by many websites to prevent abuse from “bots,” or automated programs usually written to generate spam. No computer program can read distorted text as well as humans can, so bots cannot navigate sites protected by CAPTCHAs.
What I really liked about reCAPTCHA vis-a-vis other spam-fighting tools is that, every time a comment is posted after verification by reCAPTCHA, it helps digitize books! As the website explains:
reCAPTCHA improves the process of digitizing books by sending words that cannot be read by computers to the Web in the form of CAPTCHAs for humans to decipher. More specifically, each word that cannot be read correctly by OCR is placed on an image and used as a CAPTCHA. This is possible because most OCR programs alert you when a word cannot be read correctly.
And what’s more, the developers have also thought about accessibility, so even blind people can use it! Way cool.
To learn more about reCAPTCHA, visit http://recaptcha.net/learnmore.html.