Just wanted to let you know that I've just published an android tablet app to the Google Play Store: CensusUS at https://play.google.com/store/apps/details?id=com.clcassidy.censusus.
The app uses the Census APIs combined with Google Maps v2. By tapping on the map and the navigation menus on the tablet, users are able to select locations at all levels of geography, from the national down to the tract level, and then see census data for the selected location. Tap on the map and the census data for the selected location displays. The app also has rankings reports by median income and by median income by occupation within the selected geography.
I'm hoping that the app will be especially useful for productivity users, such as real estate professionals, who can use the demographic data to help clients find a best match for neighborhoods.