GarageTunes is a small footprint music player for single Mac users and even groups.
It automatically finds all available music files (.mp3 and .m4a/AAC) currently on your hard disks, external ones included. Songs appear automatically in GarageTunes as you add them to your hard drive and automatically disappear when removed.
GarageTunes also lets you listen to music files on other Macs running GarageTunes in your local network. You can output your music files on any Mac on your network that has the GarageTunes app running.