How does this site work?

Hello Kirupians,

Was wondering how this site worked, I am new to this whole scripting stuff (pretty good with flash) but was curious how this site worked and if there was a way to create a similar site but using my domain name extension rather than there’s.

http://www.mintemail.com/

Basically its just a random email creator, but I just want to use this for informational purposes just to learn how its done and if it could be created simply.
but if I wanted to have control to all the emails ( if i sign up for a site, I won’t forget where passwords are and what not because they will be on my server) thus another reason.

Cool Beans Guys.
:stare: