I have a script that runs based on the page/site that referred the user to that page.
20 out of 400+ visitors actually ran the script. SERVER['HTTP REFERER'] apparently returned no value for the majority of them.
I have Firefox (Mac and Windows), Safari, IE and Chrome. Only my Mac Firefox browser didn't send the referer information when I tested the script so I thought it would be pretty useful.
20/400 doesn't sound useful.
Google Analytics must have something that can get the information? They seem to know every website the users have come from?