easiCaptcha
easiCaptcha is a captcha that you can add to your web forms easily and quickly, it consists of 2 php scripts, a decrypt loader folder and a configuration file that you can use to adjust easiCaptcha's preferences if you feel you want to. You need no knowledge of scripting, in fact it can be as simple as dropping the scripts and loader folder into your form directory on your server and adding two lines of php to your form. easiCaptcha now comes with easiCaptchaM which is an additional script that uses a math question rather than an image, so now you can pick from one type of captcha or another.