Information about this PHP class / application

At the moment I need to write some smart functions to get  a safe (public) form submission. This is one of the most important features in all public web applications because of all the spam bots on the internet. The data which is send to the database is validated while using some regulare expressions. 

Real world examples

At the moment there are several active guest-books I wrote in the past, I will re-use this code and the experience I got with this scripts to create a better application. Check a live example on the website from Pefina.