Mote, the Amazon S3 Music Player

Mote began as a 6-hour project and slowly changed into a 12-hour one. It takes the contents of any Amazon S3 bucket, checks for audio files and lets you play them like an album. It defaults to using HTML5’s audio tag, and falls back to Flash if your browser does not support HTML5.

Mote is clever enough to know if your browser supports any of the specific kinds of files in the bucket (say, M4A in Firefox) and if not, will fall back to Flash for those files.