MozillaLabs is has launched an experimental addon to manage your contacts. The purpose of the contact-addon is to bring the contacts offline into Firefox. Currently the services supported to import the contact info are:

Following is Mozilla’s release note:

The Contacts add-on integrates with local and web-based address books to bring all of a user’s contact data into a single database, which can then be used by browser extensions or web content.  The user must grant permission before any content can be used by a website, and can choose exactly which fields and personal records to disclose.

Download Experimental Contacts Addon