ArcGIS on Smartphones: The ArcGIS App for Smartphones and Tablets extends the reach of your GIS from the office to the field. Navigate maps, collect and report data, and perform GIS analysis using the free downloadable application from Google Play, the Apple App Store, Amazon Appstore, and Windows Marketplace. The app includes a developer focused Runtime SDK that you can leverage to build your own custom mobile applications. http://www.esri.com/software/arcgis/smartphones/index.html
Easily draw on maps and then share them with friends, completely for Free! Simple enough to be used by children, but powerful enough to be used by GIS professionals - Scribble Maps is the easiest way to draw and share maps with friends.
In what surely serves as a useful marketing tool for any business looking to target neighborhoods by consumer demographics, big business data analyst Esri has developed an interactive map that summarizes your lifestyle demographic by zip code, AKA it figures out what your zip code says about you.