Just out of curiosity:
My default browsing behavior (with FireFox 3.5) is to open links in a new tab. If I am searching something in google, I always right-click search results and open them in a new tab. If I am looking at popular links on delicious.com, I right-click and open the link in a new tab.
So I am wondering what the HTTP Referrer would show for my visits when I land on a site. If I "follow" a link from delicious by right-click & opening in a new tab, does FireFox tell the site that I came there from delicious, or does it treat it like I opened a new tab and typed the URL in myself?
I don't have any web servers that I can see the referrer for, otherwise I would test this out myself.