Hunter - Find all the email addresses related to a domain
Freshdesk - Freshdesk is a cloud-based customer support software that lets you support customers through traditional channels like phone and email, social channels like Facebook and Twitter, and your own branded community
AnyMailFinder.com - Find anyone's email address
Zoho Desk - Industry's first context-aware Helpdesk Software
AeroLeads - AeroLeads is a lead generation software which finds prospects with email and phone number.
Salesforce Service Cloud - Service Cloud integrates customer service with social networks and provides a self-service customer portal and knowledge base system.