[AChimp]

It could be that there *was* a link to your site on that page, but it has since been removed.

However, some browsers will treat the previous page that it was looking at as the HTTP_REFERRER, even though that page has absolutely nothing to do with yours. For example, on a browser that does that, you could be looking at I-Mockery, and then go to any site that was in your bookmarks list and that new site would count I-Mockery as a referrer.

Stuff like this can also happen on sites that open external links in a new, specifically named (rather than _blank) browser window, and people just don't bother to close that window as they click on each link (kinda like Fark).