I've always found the Google I/O app to be a better example than any API examples because it was built to be used in real-life scenarios and tested under heavy load of geek users with a multitude of devices. So this app works in real life.
You can still download the app from Google Play to try it out.
Here's a list of things the app demonstrates according to Android Developer's post on Google+
• Implementing responsive design with fragments and alternative resources to support phones and tablets
• Using content providers and implicit intents to navigate the app
• Using sync adapters and GCM to keep content fresh across devices in a battery-friendly way
• Integrating Google+ for sign-in, public stream participation, and as a share target
• Integrating Google Play services to include Google Maps (with custom tiles, markers, and info windows) and +1 buttons
• Integrating the YouTube Android Player API to view live streams and recorded session videos, along with 'second-screen' presentation API support
• Exposing multiple entry points to the app with home screen and lockscreen widgets and expandable notifications
Read the full Android Developerspost in Google+ for more details.
Or download the source code from here: https://code.google.com/p/iosched/