ContactRescue - Magically get your address book up-to-date and accurate
Senders - Caller ID for your email
Wall Of Me - Wall of me: all your favorite socials in a single place.
LinkedIn Sales Navigator for Gmail - Rich contact profiles inside Gmail
Clearbit Connect - Clearbit Connect is a free extension that surfaces actionable information on the people who email you.
RocketReach - RocketReach allows you to lookup email and phone for 250+ million professionals.