In this video, I show you how to create multiple iTunes libraries all on one computer. This method both saves money and allows each person (in a family, for example) to sync music of his/her own choice to his/her smartphone.
Just hold down the "shift" button, click on the iTunes icon, and continue to hold down on the 'shift" button until a dialog box appears. Then...start creating, or switching between, your libraries. Have fun!