DNSChecker.org - Check DNS Propagation worldwide. DNS Checker provides name server propagation check instantly. Changed nameservers so do a DNS lookup and check if DNS and nameservers have propagated.
Wappalyzer - Wappalyzer is a technology profilers and leads data provider. Create lists of websites and contacts that use certain technologies.
WhatsMyDNS.ME - WhatsmyDNS provides free DNS Resolution Check for checking if your DNS Records are updated in the various locations worldwide.
BuiltWith - Find out the technology behind websites
Whats My DNS - Instantly check your domain names current IP address and DNS record information against multiple name servers located in different parts of the world.
What CMS - WhatCMS.org looks at a variety of factors within a webpage to determine what CMS a website is using.