The Entertainer is one of the most popular pieces of stock music, but is difficult to get good-quality, freely-licensed copies of.
I may be talking about my own work, but I do think this is quite good. I've included:
1. An MP3 file
2. A MIDI file
3. an NWC2 file; for those who need to make tweaks for whatever reason (and use the same software as I do).
The only requirement is that you credit me, Adam Cuerden, in whatever way is appropriate for what you're doing with it (for instance, the credits of a game or video, but I doubt I could predict all possible uses). For convenience and simplicity, I've offered a Creative Commons license, as a standardised way of offering credit.
A link to adamcuerden.deviantart.com/gallery/ is appreciated, but not needed.