Thunderbird - Thunderbird is a free email application that's easy to set up and customize - and it's loaded with great features!
Google Contacts - Google Contacts is Google's contact management tool that is available in its free email service Gmail, as a standalone service, and as a part of Google's business-oriented suite of web apps Google Apps.
Geary - Geary is an email application built for GNOME 3.
Drupe - Next generation contact manager and dialer.
Evolution - Apps/Evolution - GNOME Wiki!
Simple Contacts - Contact lens prescriptions from home