Cardhop - The Mac contacts app you'll want to use.
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.
The Contact Guru - Managing your contact list so you don't have to
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
ContactRescue - Magically get your address book up-to-date and accurate