Hunter - Find all the email addresses related to a domain
AnyMailFinder.com - Find anyone's email address
EmailMatcher - Find anyone's email address in a matter of seconds, for free
AeroLeads - AeroLeads is a lead generation software which finds prospects with email and phone number.
LeadGibbon - Access millions of business contacts, with verified email addresses and phone numbers
GMass - GMass allows you to easily schedule emails, send out mass emails and mail merge campaigns and more with Gmail! Click here to learn about more features!