Any track from SMB 1, 2 or 3 for the NES is fair game.
Mash-ups and medleys are okay (you can even use multiple games in one track if you want), just don't do it for the sake of doing one. Ultimately my bonus vote will be based on production value and creativity, while maintaining all important parts of the source.
A bunch of .mid files are available at http://www.vgmusic.com/music/console/nintendo/nes/ (Search Super Mario Bros and you wont have to scroll).
Start: on 2/22/16
Deadline: on 3/8/16
Voting: on 3/10/16