SeoQuake is a Firefox extension that allows you to view statistics of search engine parameters on the fly. SeoQuake for Mozilla Firefox consists of three functional parts: SeoToolbar (requested parameters are shown in a separate toolbar in the browser), Seobar (requested parameters are shown in a separate, fully customizable CSS/HTML block), and output of requested parameters on Search Engine Result Pages (SERPs).
SeoQuake helps a lot with SEO analysis of any website. It shows me Google PR, Google last cache, some search engine indexes (Google, Yahoo, Bing, Baidu, and Yandex), Alexa rank, Compete rank, Semrush rank, DMoz index, delicious index, Digg index, Technorati index, domain age, keyword density, and many more.
See the screenshot below:
