Advanced Eyedropper, Color Picker, Gradient Generator and other colorful goodies...
Draw a ruler across any webpage to check the width, height, or alignment of page elements in pixels.
Wappalyzer is a browser extension that identifies software on websites.
Help make Firefox better. The Add-on Compatibility Reporter enables you to report if the Firefox add-ons that you're using are working properly.
Display the Google PageRank, Alexa rank, Compete ranking and SEOmoz Linkscape mozRank anywhere in your browser, along with fast keyword density analyser, keyword/nofollow highlighting, backward/related links, canonical links, WHOIS, robots and more.