The Higher Education Opportunity Act requires all colleges and universities to offer legal alternatives to unauthorized downloading. The list at the bottom of this page includes all of the legitimate online services we're aware of.
Note: Some of the sites listed below provide some or all content at no charge; they are funded by advertising or they represent artists who want their music distributed for free, or for other reasons. Just because content is free does not mean it's illegal.
On the other hand, you may find websites which are not on the list offering to sell content. Just because content is not free does not mean it's legal.
This list comes from Educause.