Tutorials/Programs and editors/Minecraft Note Block Studio

The Minecraft Note Block Studio (Previously known as the Minecraft Song Planner) is a music editor for Minecraft. With it, you can compose complex note block songs without any redstone knowledge whatsoever in a simple and straightforward interface. Unless you are planning on importing your song into Minecraft, the 2 octave limit of note blocks won't be a problem and you can also add your own instruments.

You can download this program from its official Minecraft Forums topic, here.