RefControl

RefControl is an extension for Firefox that lets you control what gets sent as the HTTP Referer on a per-site basis.

This can be useful in a number of situations:

Privacy - Perhaps you think webmasters don't have any business knowing where you found the link to their site. You can configure RefControl to not send the referrer to any site except for ones you explicitly list. Broken sites - Some sites perform misguided referrer checks in the name of "security". These checks don't add any real security since the referrer is easily faked and can often cause problems when the browser's behavior changes. You can configure RefControl to send these sites whatever they are expecting and work around this kind of problem. Fun - Send humorous things, secure in the knowledge that they are being written into the server's log file for the amusement of anyone who might later discover them there. Ok, maybe that's not much fun, but RefControl will let you do it anyway.