The Rock and Roll Hall of Fame and Museum, located in Cleveland, Ohio.
http://rockhall.com/

Allmusic provides artist biographies and discographies for artists in a wide variety of musical genres.
http://www.allmusic.com/

Invention and History of the Electric Guitar, from the Lemelson Center for the Study of Invention and Innovation
http://invention.smithsonian.org/centerpieces/electricguitar/index.htm

The Memphis Rock n Soul Museum
http://www.memphisrocknsoul.org/

Motown Museum
http://www.motownmuseum.org/motown-sound/

Sun Studio
http://www.sunstudio.com/