Bulk Email Verifier - Clean up your large mailing lists before you use them. Clean list increases your reputation in MailChimp, AWeber, or Campayn.
FullContact Card Reader - Automagically scan biz cards into LinkedIn/Gmail contacts
Email Verifier - Email verifier app lets you verify email.
Clearbit Connect - Clearbit Connect is a free extension that surfaces actionable information on the people who email you.
Email List Verify - The Fastest Way to Improve Email List Deliverability and ROI
ZoomInfo - ZoomInfo is a B2B database providing detailed business information on people and companies.