OneTrueFan is a Foursquare like service for websites. You need to install a browser extension and a browser bar will start tracking your Web visits. Each time you go to a new domain or subdomain, you get 10 points. For each visit to a subsequent new page, you get an additional point. If you have more points than any other fan, you are the One True Fan.
Users will also get 5 points for sharing content from OneTrueFan to sites like Twitter, Facebook, Delicious or any other. They will also be able to see a leaderboard of users who have been sharing content. All of this info can be seen on the bottom of a publisher’s website.
OneTrueFan is currently in private alpha. You can request for an invite at their homepage.