For the last year or so I have been contributing to Ambio. This is an android app created by Chris Newby which allows you to build and purchase soundscapes. Those soundscapes can be used as either alarms or for a better way to fall asleep. This is what the author himself says: "Ambio lets you create perfect ambience and whitenoise so you can relax, ponder, and sleep better :)" Here is the ambio information about Ambio.
Other than bug fixes my contributions are centered around creating workarounds to problematic issues with the android system. For example: looping audio sometimes causes gaps in playback, newer APIs to provide continuous playback don't interact well with looping audio, native audio interfaces change during different versions of the NDK, even when forcing fixed orientation in activities change events still require reconstruction of cursors and database connections.