If you are headache about what to do to your plain wall, Secret Pie Shoppe has a brilliant idea you may like.
This project is extreme low cost, all you need are some music sheet (you can print out from the internet), scissors, glue and a happy heart :p!
See the final effect:
The living room
When the hearts are ready, you can fold a line then glue it like a cube shape to stick at the back of the heart, like so:
With patience glue it one by one on the wall:
Of course you can arrange any shape you want to make the best effect. Hearts flow in the melody!!