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.
Cardhop - The Mac contacts app you'll want to use.
Open Contacts - Open Contacts is an advanced address book program for managing contact info of individuals and...
FullContact Card Reader - Automagically scan biz cards into LinkedIn/Gmail contacts
Keep In touch - Keep in touch with thousands of people
Kontact - Kontact is the integrated Personal Information Manager of KDE.