One of the great things about the pony fanbase is all of the wonderful original music that is created. For instance, there are songs like Avast Octavia's Plot or Rainbow Dash Shylenol.
A very nice guy, who goes by chaoszero64, put together some awesome music resources for these two songs. For starters, here is the sheet music for Avast Octavia's Plot as well as a midi. You can also see just the parts for cello, viola, violin, and a second violin. Then there is a midi and sheet music for Rainbow Dash Shylenol. It's really great stuff!
Thanks so much for sharing your musical talents, chaoszero64.