The API Demos application includes a variety of small applications 
that illustrate the use of various Android APIs. It includes samples of:
  - Notifications
  - Alarms
  - Progress Dialogs
  - Intents
  - Menus
  - Search
  - Persistent application state
  - Preferences
  - Background Services
  - App Widgets
  - Voice Recognition
  - And many many more...

Api demos is designed to use the compatibility library "android-support-v4.jar".
It is available through the SDK Updater in the "Android Compatibility package".
Once downloaded, copy the jar file into the ApiDemos project libs/ folder.
(If using Eclipse, add it manually to the project build path).