Have you seen those amazing sites where you can add your site to a list, fill in a form, pick items from a shopping list, vote or whatever?
It's done by magic, or special website software scripts (same difference!).
Some of these scripts are available for you to include on your site, for free and gratis. The sites say their scripts are simple, and easily installable. Groucho Marx also said a few things.
Some of the CGI sites are: