Simple Contacts - Contact lens prescriptions from home
Drupe - Next generation contact manager and dialer.
FullContact Card Reader - Automagically scan biz cards into LinkedIn/Gmail contacts
Webby - Webby allows to use Facebook, Youtube or any web app as a regular desktop apps, integrated with the...
GNOME Contacts - All your contacts in one place
Nextcloud Contacts - The Nextcloud contacts app is a user interface for Nextcloud's CardDAV server.