Funambol - Funambol is the leading provider of platforms that power many cloud services.
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.
ownCloud - ownCloud is an open source project enabling businesses to host their own cloud storage while maintaining regulatory and compliance needs.
Drupe - Next generation contact manager and dialer.
fruux - Free service that takes care of your contacts, calendars and more so you don't have to.
Simple Contacts - Contact lens prescriptions from home