Well for those of us who work in an office we find that our headphones are on a lot.  This site is very similar to Pandora but with a slight twist.  I think it is easier to build custom radio stations and it automatically selects music you may like.  Great for creating the never ending play list to run while you are at work.  They are in private beta right now but I managed to get an invite inside and so far so good. Also I think the quality of music sounds a little better then Pandora.  Also it is a little nicer because it shows you all the related artists and you can add them to your play list.  The more you add the less they suggest other people and the less you add the more they play their recommendations.