Simple Android App w/ Source Code - Android Studio app example. Sample project with source code (free download).
The source code for the course "Building Scalable Apps with Google App Engine".
Open-Source Android Apps
Source code for the WSDOT Android application
Android application used to control the Open Source Rover
Open source Android app for Faveo Helpdesk Community Edition
εxodus Android application
This is the source code for Thunderboard application for Android.
Open Source Messenger App For Android - Real-time Messaging, Voice and Video Calls
Telegram for Android source