Pandora is a site you can go to, type in the name of one artist, genre, type of vocals, anything down to the tiniest detail and get perfect matching songs played for you over and over. Nothing can top this! They are slightly limited due to legal issues, but you can listen to full songs like all day that are related to whatever you like down to the detail!
You can create different channels as well for those who were wondering. As many as you want, each one dedicated to bringing you music related to what you specify. Give songs a thumbs down, up, or a zzzz which means to never play it again. Thumbs up, play it more often for everyone, Thumbs down, play it less for everyone. Interesting Concept there.
I first found out about Pandora on the GigaOM show, and i thank him so much for letting me know about something so amazing. So go there and add me! Wham! Radio, is where its at! I hope you all consider this site. Nothing is like it!
UPDATE You can also bookmark people, songs, artists, genres, everything! So you can listen to it in the future! Nothing gets better than this. And the only things you wont like about it, are the things they cant do due to legal issues. And they arent even that bad, such as listening to a song that you listened to just now again, thats ‘free music’ so they cant do it, they can only give you a sample, and links to buy it from Amazon and iTunes!
One last thing i think is amazing, is how you never stop your music from playing! If you click a link on the site, NEW WINDOW! Never stops playing. Everything is in a flash player, so its all RIGHT THERE. Amazing, go to it, sign up, you will never regret it.