Diaspora* is completely decentralized, and any person from any pod can communicate with one another! You can register at any of these other pods as well. You can also choose to set up your own pod if you'd like.
Tor makes it possible for users to hide their locations while offering various kinds of services, such as web publishing or an instant messaging server:
diasporaaqmjixh5.onion
Make Diaspora even better! Fork the project on Github make some changes, and submit a pull request.