Recently, my brother turned me on to Pandora, a different kind of internet radio service. With Pandora, users can create radio stations based on their own musical preferences, such as a certain artist or song, for instance. The station then plays music for you according to a predetermined set of criteria developed over a period of six years by a group of musicians and music lovers, called "The Music Genome Project."
However, it doesn't stop there. Since the site utilizes Artificial Intelligence technology, it "learns" from user input, in order to make better selections. The user can give a "thumbs up" or "thumbs down" to selections, and even bookmark songs or artists they like. This allows the AI to tailor your station to your liking. Of course, this requires users to be active, rather than passive, listeners, at least initially.
You will undoubtedly find that the service will introduce you to new artists you have never heard before, all within the genres you habitually listen to. However, there is always a danger that listeners will never break out of their stylistic "boxes" with this sort of service. If you really want to challenge your listening habits, you should occasionally listen to one of the many freeform radio stations that can be found on the internet. If you keep notes of your findings, you can then go back to Pandora and create more stations based on the new musical styles you have heard!
Go into the world and discover new music!