Pandora (Internet radio)
Pandora is a popular, free internet music site. Pandora asks the user to provide a favourite song, then serves up an endless series of songs which share certain musical characteristics such as minor key tonality, rhythmic syncopation, and vocal harmonies. Pandora refines its sense of what you like in response to "thumbs up/thumbs down" feedback for each song.
Pandora is rapidly growing, and has recently been deployed to cellular phones. The Pandora media player utilizes Adobe Flash, allowing for cross platform portability.