pagead2.googlesyndication.com/pagead/ads?client=yyyy&dt=11111&...url=http%3A%2F%2Fexample.com%2Fkeyword.html...
So you can extract the Site from the "url" field of the referrer.
[edited by: eWhisper at 8:34 pm (utc) on Jan. 23, 2005]
[edit reason] Delinked URL [/edit]