Clearbit - Clearbit provides Business Intelligence APIs
Lead Connect - Send Automate LinkedIn connection request and scheduled followups with mail merge place holders.
ZoomInfo - ZoomInfo is a B2B database providing detailed business information on people and companies.
Salesflare - Simply powerful CRM. Automates your data to build better relationships and make more sales.
InsideView - InsideView aggregates and curates all the company and contact data, news and social insights, and professional connections you need to do business better.
Ebsta - Capture every email and business contact inside Salesforce.