Google Contacts - Google Contacts is Google's contact management tool that is available in its free email service Gmail, as a standalone service, and as a part of Google's business-oriented suite of web apps Google Apps.
BuiltWith - Find out the technology behind websites
Google Calendar - Spend less time managing your day & more time enjoying it
Wappalyzer - Wappalyzer is a technology profilers and leads data provider. Create lists of websites and contacts that use certain technologies.
Apple Contacts App - Access and edit your contacts from personal, business, and other accounts with the Contacts app.
What CMS - WhatCMS.org looks at a variety of factors within a webpage to determine what CMS a website is using.