Wappalyzer - Wappalyzer is a technology profilers and leads data provider. Create lists of websites and contacts that use certain technologies.
SalesOptimize - Selling to online retailers? Revolutionary sales lead generation search engine driven by deep web analytics
BuiltWith - Find out the technology behind websites
Sparkroom - Sparkroom streamlines school marketing and operations.
WhatRuns - Extension that helps you identify technologies used on any website at the click of a button.
What CMS - WhatCMS.org looks at a variety of factors within a webpage to determine what CMS a website is using.