1. An online music purchasing system, comprising: a radio service operating on a user's computer and configured for receiving and playing digital radio representations of media content in near real-time in a radio session; a content server configured for serving the digital radio representations of media content to the radio service; a radio sequence server configured for serving a sequential list of currently-playing and previously-played media content of the radio session to the radio service; an account server configured for receiving a signal indicative of a user's desire to purchase a file of one of a currently-playing or previously-played media content; and a download manager, configured for downloading the file to the user's computer according to the signal indicative of the user's desire to purchase the file.