An app that gets me a couple cents a day in bitcoin.
I downloaded several apps that give bitcoin for watching ads every 30 minutes on my old phone. This program opens each app every 30 minutes, watches the ad, and then closes the app. If this app runs for 24 hour straight it will earn roughly $0.42! That's almost $3.00 a week!!
This app wasn't made to make money actually. It was just a fun side project and I personally I think it went pretty well. It requires root access in order to simulate taps to the screen.