I hade added reCaptcha image verification to the clients Article Friendly article directory script due to teh amount of spam he was getting on his signup form. This worked for a while, but then spammers wrote scripts to crack recaptcha and auto submit. I added text captcha to the form to stop spam from getting through.
Also this week, I added text captcha form verification to several other clients’ PHPforms. They were using Java Script validation on the web page. This is easily bypassed by simply disabling Java Script . Using PHP to validate the form data on the server side, it is much harder for spam to get through.