With Android, applications can integrate features, data from other applications and information through web API’s, as well as use all of the hardware sensors on the device such as the camera, GPS, accelerometer and the compass. This feature is entitled Applications Without Boarders.
Zebra Crossing is a fantastic example of one such application. It uses an open-source library used to decode barcodes using the camera. Zebra Crossing can recognize your everyday barcodes as well as 2d barcodes called QR codes. One example, scanning a barcode on the back of a business card will give you the contact information allowing you to directly call the number, email the contact information or allows you to save the contact without entering in the information. Zebra Crossing also publishes information (intent) so that other applications may use it as well.
Other developers now have to ability to develop similar applications without having to do all the work. One application that uses the open-source library, stores books on your handset for readers on the go then has the ability to scan the barcode on the back of a book and take the intent from Zebra Crossing and use it to find book information and directly download new books to your library.
Panoramio uses GPS to find your current location and link it to the most popular photos taken within your area. From there you can learn more about that particular photograph and even locate where it was taken on a map. Panoramio also uses the compass feature to provide you with a radar view for walking directions to where the photo was taken as well as your distance from the location.
-Daniel