I read a new story on Mashable today about a new bookmarking service called Youlicit. Yeah, I know… just another bookmarking service. This one looks pretty interesting though. when you arrive at the home page you have a search bar similar to the default Google search. You can perform regular searches, but you can type in a specific domain/URL and it will attempt to find other sites that have similar content. Not only does it do this using some computer heuristics, but it also gathers data from user-suggested similarities from the bookmarking side of the service. They also have a few FireFox addons to enable you to quickly access all of their features.
You can check out Youlicit or read the original article on Mashable titled, Youlicit Uses Bookmarking Tools to Minimize Your Online Search.