PBS
Pbs: American Roots Music
If teaching a unit about the history of popular music in America, this PBS web site supporting their four-part TV broadcast of a few years ago would make a great resource. Includes lesson plans and oral histories too.
Rock and Roll Hall of Fame
Rock & Roll Hall of Fame: Bill Monroe
Offers interesting biographical background details on "the father of bluegrass music", Bill Monroe, a 1997 inductee into the Rock and Roll Hall of Fame. Includes a timeline of key events, recommended reading list, and essential songs.