DJDelta0 was the first pony fan to send in resources for the finale. He tackled three of the seven (!) finale songs, creating some really excellent piano reductions.
The songs DJDelta0 has done are A True True Friend (in the embedded video), Morning in Ponyville, and What My Cutie Mark is Telling Me. For each of the songs, DJDelta0 also shared sheet music, an mp3, and a midi. You can find those in the descriptions of each of the videos, and we'll be adding them to the Season Three resource page in the near future.