I have noticed someone doing something strange. They have configured their browser to report the referrer as Google.
XXX.XX.XX.XX - - [08/Jul/2005:16:26:28 -0700] "GET /index.php?op=ViewArticle&articleId=492&blogId=2 HTTP/1.0" 200 28062 "http://www.google.com/" "Mozilla (X11; I; Linux 2.0.32 i586)"
I can't image that there are web servers that allow different content when the referrer is the home page of Google. Especially since most valid referrers from Google will contain a the search query. (I really doubt that I am listed on Google's main page.)