People!

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.

FullContact's apps let you keep all your contacts in one place, automatically up-to-date. This social contact management software automatically cleans your contacts, enriches them with social profile data, and continually syncs them across devices with all your contact sources. You can also merge duplicate contacts, scan business cards, capture email signatures, and more.

Alternion is a social hub and communication center that enables you to combine and manage all your social web and email in one place.

fruux is a free service that takes care of your contacts, calendars and more so you don't have to. Never manually copy contacts and calenders between your devices again!

With Memotoo, sync all you want !

With Free Address Book - Free Phone Book you can note the addresses, phone numbers, mobile, fax, company name, country, city, website address and email addresses of your contacts and partners.

ID Book is a handy, easy to use application specially designed to offer users a simple address book.

Syncs contact between various third-party services and helps to clean them up and merge data.

E-Z Contact Book is a free easy to use yet powerful Windows program to store and manage contact information. You can use it as a business directory, customer database, or a personal contact address/phone book.

es-Builder is a flexible, customizable, friendly, powerful and unique database manager for private personal use.

Pingboard is your employee directory, org chart, & out of office calendar

Address book program providing unified, flexible and simple interfaces for you to manage and lookup contact info of people and organizations.

KAddressBook stores all the personal details of your family, friends and other contacts.