Firefox SEO Extensions
This plugin provides additional information for every search result listing on Google. Also, it can be turned on and off with one click, so it doesn’t bother you while you’re browsing casually.
If the icon is colorful, it is on:
In plain English, SEO for Firefox tells you why certain things rank, so you don’t have to do the guessing game any more.
The plugin will give you pieces of information such as: Google PageRank of a webpage, domain age, number of backlinks (including .edu and .gov), number of bookmarks on Delicious, and more.