Android custom UI xml elements

http://developer.android.com/guide/topics/ui/custom-components.html

http://kevindion.com/2010/12/android-odometer-ui-tutorial-part-1/

http://stackoverflow.com/questions/4910307/android-custom-view-standard-element-how

http://blog.pocketjourney.com/2008/05/02/android-tutorial-42-passing-custom-variables-via-xml-resource-files/