Appleseed
Appleseed (or maybe AboutUsSeed) is part of the GreenThumb browser plugin.
A user that has explicitly enabled Appleseed communicates their support for the AboutUs project every time they visit a website, and invites the proprieter of the website to improve their page on aboutus. The invitation takes the form of a referer header that lists the most relevant page on AboutUs so that this information shows up in the webserver logs and attracts the attention of the webmaster.
