GlassMusicPlayer is an mp3 player for Google Glass. It does not require an internet connection, it plays files off of your internal storage (on glass)
To use, adb sideload the apk to your glass as any other. The music files must be anywhere on the sdcard partition on your Glass.
To trigger the app, say OK Glass...Play Music. It will play the songs in the order they appear in the folder structure. You can also shuffle your music so it is random.