Website that discusses the power of words in popular music.
This website isn't always completely accurate or balanced, but it's a good starting point for popular music, especially for identifying newer acts. It has a moderately long list of links to performers at the end of the entry.
This is a very handy Columbia Music Entertainment website with a short history of Japanese traditional music, brief explanations of genres, explanations and pictures of instruments, and short samples of several pieces in each genre. Be aware that you will need RealPlayer to use this site. Sorry.