iHeartRadio is an old favorite of mine that lets you stream radio from over 1,500 live radio stations or create custom stations based on a song or artist. The best thing about it, though, is that your custom stations are completely ad-free.
Live radio stations from all over the U.S. are available, including everything from pop, country, rock, electronic, and urban, to talk and college stations. You can browse by genre or location and listen to music until you hit a song you don't like, then hit the Scan button to move on to another radio station (no matter the location) that offers similar music. If you like a particular station, you can save it to listen to again later.