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.
Hunter - Find all the email addresses related to a domain
Drupe - Next generation contact manager and dialer.
AnyMailFinder.com - Find anyone's email address
Simple Contacts - Contact lens prescriptions from home
Norbert - Norbert is an online tool that helps you to find anyone’s corporate email address.