Evercontact - Your contacts always up to date and automatically with Evercontact.
ContactRescue - Magically get your address book up-to-date and accurate
Pobuca Connect - Connect with your contacts.
Cardhop - The Mac contacts app you'll want to use.
CRM-gx - Contact Management
Clearbit Connect - Clearbit Connect is a free extension that surfaces actionable information on the people who email you.