Metroid doors principle in minecraft
In the Metroid serie, as you progress through the game, you get new weapons whichallow you to acces new areas that where previously locked. For example the white doors can be opened only by the ice beam while the red doors requires the plasma beam.
With this idea in mind, I end up with a small redstone contraption which use music discs instead of laser (there aint no pew pew in minecraft ... yet).
The way it works is that each music disc will output a different signal strength when inserted in a jukbox, knowing that it's possible to check if the strength of the signal is what we want and output a signal to a door or whatever we want.