It depends on the iPod... no matter what you can get it off though.
On regular iPods you need to enable disk use and hidden folders, and browse to one of the folders on the iPod (With a bunch of folders inside of it labels F00, F01, etc) and that's where your music is.
On the touch and iPhone, you'd need to SSH into your iTouch/iPhone and go to the right folder and get your music off. The folder is all based on version, though, cuz Apple is a bunch of jerks and change folder paths in a lot of firmwares.