Raspberry LED

Install the app on your Android device and run a python script on your Raspberry Pi.
The Raspberry must have a LED connected to pin 40.
Both devices must be connected to the same network (like your home WLAN).
Tap the plus sign in the top right corner to type your Raspberry IP address and port (the python script will show you this values). The app will save the address and port for future use.

Python script: http://profejuan.pe.hu/raspberryled/ledonline.py

All set! Enjoy!