Internet radio USB's

I've seen them not only in Fry's ads but also in some mail-order catalogues I've received on occasion.Supposedly you can listen to thousands of radio stations from all over the world just by plugging the device into a USB port and having an Internet connection,but are there are so many seiyuu radio shows that I wouldn't know where to start,though some Japanese radio stations don't have an online presence yet...

Happy 31st birthday to Akemi Kanda...