I use Pandora for music at work. I think Pandora is so handy and brilliant. It's like a satellite radio on your desktop. Here is a screenshot, I recommend clicking on it to see the full resolution view.
I use the Opera web browser to play pandora. I can cinch up the page to just be around my Pandora player view and Opera remembers where I was (at Pandora's site playing music), how I sized the window and where I put it on the screen (Mac OS X). This means I can quit Opera and reopen it and it positions my Pandora window and begins playing music again, Just like an app. This is Opera 9.21.
It's also helpful if I have to use my browser, say Firefox, in a proxy for work. I often need to quit Firefox or re-point its proxy for work uses. All of this would interrupt my Pandora player, so having it in another browser is very handy. Especially one with the behavior of Opera.
Pandora introduces me to music I might like I might never have heard and Opera makes it work almost like a music application. It is an excellent experience for sure.