Your demo, had me a little confused, but based on your oneliner and other peoples comments it makes more sense.

That said...

Great little concept.

* If your majorly concerned about dodgy injections of referrers. Might be worth taking a leaf out of bit.ly and linking a system to filter out urls based on something like http://www.surbl.org/.

* Maybe even include the ability to offer unique things to visitors from wherever they might have just come. A unique article only they can see, whom knows.

* What sort of reporting could / would be good for the site owner?