Similarius

Similarius helps you find similar sites with just one click. With Similarius you can find similar site to the site you are currently viewing simply by clicking a button in address bar. Similarius integrates with Google, Bing and Yahoo search results, so you can access similar websites directly from search results page without even visiting a site. When you want to find an alternative website to what you are seeing in search results, simply click "Get Similar Sites" link from Similarius and we'll provide you a list of alternative sites.

Requirements:

Mozilla Firefox 3.6