According to their About page, The Free Music Archive was inspired by the Creative Commons and open source software movement. "Radio has always offered the public free access to new music. The Free Music Archive is a continuation of that purpose, designed for the age of the internet."
Directed by freeform radio station WFMU the site offers free legal music downloads, information about the contributing artists, and links to the artists' websites.
It's a great site, and tailor made for those of you who like to explore!