Sustain helps throttle communication. Users can download news and RSS feeds relevant to their contacts and instantly share them. Users can also see which contacts would be the most likely to be in their vicinity. Unique features like auto-replies that trigger when particular calls are missed and reminders that pop-up when particular calls are answered allow users to maintain seamless interaction with their contacts.

http://code.google.com/android/adc_gallery/app.html?id=43