BuiltWith - Find out the technology behind websites
CRMfusion - CRMfusion is a suite of data quality and data integration tools that integrate well with Salesforce.
Wappalyzer - Wappalyzer is a technology profilers and leads data provider. Create lists of websites and contacts that use certain technologies.
MapAnything - MapAnything is a mapping and geo-analytics solution available to Salesforce users that provides mapping, schedule planning, and more.
What CMS - WhatCMS.org looks at a variety of factors within a webpage to determine what CMS a website is using.
Oceanos - Oceanos is a contact data management solution.