How can I create a website like rickroll.be

[FelixT]

How can I create a website like rickroll.be.
Users sign up, then recive a link (something like http://www.rotzooi.net/r/r-22-). On that page it says:
You got rickrolled!
FelixT rickrolled you and 9 others. Please tell if you know how

[nafirici]

For the link, you could concat the users id from there account on your system and timestamp and then run it through a hash, such as md5 to create the unique link for them to send out. Then, have a page that accepts these dynamic hashes and when someone goes to the page, store the ip address and set up a logging table that you can do a count against.

That would be the basics where I would start.