Meet the Water Symphony from Can You Imagine: a neat gadget that produces music with falling water drops. It has 24 musical instruments for you to choose from. It also has a timer and auto mode. You can change the tone of the music and speed by twisting the top tube.
To get the best results, you are going to need distilled water. You also need to make sure each water drop falls onto the center of each key. The above video shows it in action.