Have you ever stuck an Arduino in a hard to get place such as under the house and then realised that you want to upload a firmware revision? This can be a very frustrating situation, however, with the simple addition of a Bluetooth module it is possible to avoid this problem. Amazingly it is possible to program an Arduino over Bluetooth. For added flexibility there is even an Android app, “Bluino Loader” which allows you to upload a sketch to an Arduino from your smartphone. For step by step details of how this is possible, checkout the following link.