Updated on 06.08.2016
Controlling an Arduino over Bluetooth from Android using App Inventor 2
Here is an example of controlling the Arduino over Bluetooth using a HC-06 bluetooth module and an Android app. The example uses an Arduino Nano but other Arduinos will work just as well. A HC-05 module can be used stead of the HC-06.
The Android app was created in app inventor and the aia file can be downloaded at the bottom of the page.