need simple tracking script

[adamjthompson]

I need a PHP script that would do the following:

Small snippet of code would be added to all pages of website. This code would take http_referrer info and save it in a cookie or something.

Code would be added to thank you page after shopping cart. This code would take the info stored in the cookie or wherever and save it to an output file or form it into a table.

This simple code would allow me to track where my sales were coming from...anyone know of anything like that...or similar?

I prefer free, but low cost is OK. :p