ZZEE Human Pictcha is a protection in a form of an image (a captcha), which can be embedded inside your web forms, and which will filter out various forum spam, guestbook spam, form spam, signup spam, password attacks, etc.

It is a library and a set of tools and examples for PHP and can be used with Perl as well.Human Pictcha is fairly easy to install and embed into your existing PHP or Perl forms.

You can download a free demo version to see if it is compatible with your web site and how easy to use it in your forms.