A website that has audible sample tracks?

spotify.com and mog.com if you want full tracks. amazon.com, itunes.com and emusic.com for partial tracks. I'm sure there are lots of others.

As Elizabeth said, Pandora is one of the best ways to find new music and if you take the time to 'train' the software by giving songs thumbs-up or thumbs-down and using the 'more like this' function you can fine tune a station to your liking.

The premium subscription, Pandora One at $36 dollars a year, is definitely worthwhile. There's no advertising, you can skip as many songs as you like and the music stream is higher quality than the free version.