A new Firefox extsnion is around and is called SEO for Firefox. It gathers a lot of search engine data about a site and presents this data to you, helping you to get a clearer picture about the site’s positioning on the web. The data that the extension pulls out for you includes the number of links pointing to a domain, the age of a page, how many pages of a site are indexed (by Google) and many more.

Give it a try; installation is simple and fast and the extension also works on Flock (tested it on my Flock browser and it works just fine).