CBS is buying Internet customized radio streamer and social networking site last.fm for $280 million. The UK-based site has over 15 million users worldwide and over 4 million in the United States.

last.fm allows listeners to select favorite artists and hear streams tailored to their tastes. Users can share their playlist information with others.

last.fm's management will remain in place. The site will retain its separate identity, although it may incorporate other CBS radio programming.