.referer

This script is neat if you want to know where your visitors come from without: a) Installing a ugly sitemeter-type thing. b) Using bloated software that has a ton of functions you don't need. c) Uploading a bunch of files and then reading a manual to install it. This little script simply saves HTTP_REFERER into a file and adds a timestamp. No database needed. It's only 37 lines of code and can save an unlimited number of referrals. Just include the script on the page(s) you want to track referrals from. Easy as pie.