For lyrics, there is a great site called Rap Genius. You can look up lyrics to your favorite rap songs, and there are explanations and annotations. "Our aim is to critique rap as poetry." From the main site, you can also get to Rock Genius and Poetry Genius. Annotations are moderated, but keep in mind that this is a community-run site, like Wikipedia. Fun to look at though!

Pandora is free personalized internet radio. It's a great way to discover new artists and genres.  Simply enter a favorite artist, track, comedian or genre, and Pandora will create a personalized station that plays their music and more like it.

Pandora is powered by the most comprehensive analysis of music ever undertaken, the Music Genome Project: a project started over ten years ago to capture the complex musical DNA of songs using a large team of highly-trained musicians.

The Library of Congress National Jukebox collection includes over 10,000 recordings made by the Victor Talking Machine Company between 1901 and 1925.

Visit other Library of Congress historical audio recordings at  the American Memory Collection,