UI Movement - The best UI design inspiration, daily
BuiltWith - Find out the technology behind websites
UI Garage - Specific mobile and web design patterns for your inspiration
Wappalyzer - Wappalyzer is a technology profilers and leads data provider. Create lists of websites and contacts that use certain technologies.
patool - patool is a portable command line archive file manager
WhatRuns - Extension that helps you identify technologies used on any website at the click of a button.