Google has recently launched Google Contact Manager. Similar to Gmail contact manager, it is a standalone version that lets manage your contacts more efficiently.

Through Contact Manager, you can create groups, add multiple email, phone, or home addresses and even adjust chat preferences for your contacts.  You can also import your contacts from other sources or export the ones you have currently.

As per Google Blog:

People who regularly work in teams should check out the recently released standalone contact manager: http://www.google.com/contacts. It lets you manage your contacts and put them into groups.

When you share a document in Google Docs, just click Choose from Contacts to pick one of these groups. There’s no need to enter your collaborators’ email addresses individually. The groups you create or modify while using Google Docs are stored in the contact manager and can be used across other services like Google Calendar, Picasa Web Albums, and Gmail.

You can find the standalone contact manager here: http://www.google.com/contacts.