If you've installed toolbars to let you see the Google PageRank and Alexa ranking of the sites you visit, you might like this Firefox extension called SearchStatus. SearchStatus shows the current PageRank, Alexa rank and Compete rank (I'd never heard of it) in your status bar, or almost anywhere else you like. The attached screen shot shows the SearchStatus installation on Firefox on my Mac.
SearchStatus for Alexa and PageRank
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