Shoutcast.com is a directory of streaming internet radio stations. You can browse the list by Genre or you can use a keyword search. At the time of this writing there were 10,274 radio stations in the list. The types of music they have links to are as varied as you would imagine from an internet based radio station.. everything from the most popular of pop, to the most unique and ecletic stuff you've ever heard.

The only problem you might have with listening to / ripping internet radio is that if you are behind a firewall that blocks you from connecting to certain ports (for example at work) it might reduce the number of stations you have access to. For example, at my workplace, they block outgoing connections to all but the most common ports (http-80, ftp-21, ssh-22), so this means that I can only listen to internet radio stations that transmit on port 80 without the use of a proxy. This problem is usually non-existant in your typical home setup, so it's better to rip your music there (for this and other obvious reasons).