Savi People is a universal communicator for your contacts and major social networks. Toss in your credentials for Twitter, Facebook, and/or LinkedIn, and it links all your contacts together in its own database; Savi People doesn’t overwrite any of your Contacts data unless you explicitly tell it to. You can then choose to communicate with someone or a group however you want—email, FaceTime, Twitter DM, an @ mention, and so on. You can just post to social networks, too.
I got to help beta test, and I really like it. Savi People is pretty useful, even after the Twitter and Facebook features Apple built into iOS 6. Plus, to celebrate the launch, Savi People is on sale for just 99¢ in the App Store.