Band in a Box includes many (probably hundreds) demo songs which showcase the different musical styles available to the program. These demos offer a quick way of auditioning styles to determine which to use in your own compositions. The styles cover nearly every genre of music.
The demos are also a rich source of musical ideas in their own right. Many users spend hours simply listening to the demos for entertainment and inspiration.
Musicians may use the demos for practice in different genres. It's very useful for a rock bassist to improve his chops by learning some latin and the demos are a quick way to do this.