Unify Your Contacts Using Cobook
Having a single address book that you manually maintain is not realistic today. With different contacts on Gmail, Facebook, Twitter and LinkedIn among others it's important to have all your contacts unified and searchable in a single place. I've tried numerous "unified address" book services but my favorite by far is Cobook. It's available on Mac, iPhone and iPad with an Android version in the works.
I use Cobook to unify my Google, LinkedIn, Twitter, Facebook, Instagram and AngelList contacts. After authenticating your social accounts your contact's entries in Cobook will have active tabs for the social services you're connected with them on. An additional cool feature is the latest content posted by that contact for things such as Twitter or Instagram is displayed inline within the app.