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
- Background Services
- App Widgets
- Voice Recognition
- And many many more...

Update: The following are some of the new demos for Android 4.0:

- Settings Action Provider
- Share Action Provider
- Collapsible action view
- Custom fragment animations
- Service bindings
- Full screen UI modes
- Stylus and hover support
- Switch widget
- Accessibility Node Provider
- Window Querying Accessibility Service
- Custom View Accessibility