This is a python script that will automaticly mount any usb drives, find all mp3's on that drive and play them all on on a playlist that repeats.
install Mplayer
sudo apt-get mplayer
ALWAYS install in /home this is currently hardcoded
cd /home
sudo git clone https://github.com/Sheaffy/AutoPlayUSB.git
sudo nano /etc/rc.local
Put in rc.local
sudo python /home/AutoPlayUSB/init.py &
exit 0