That is the time to turn to Pandora, a site created by the Music Genome Project.
Tell Pandora a favorite artist, genre or song and it will start playing a whole string of music chosen based on that favorite. It is so much fun...a great way to hear new music that is similar to something you love (and to have a personalized DJ service for your gathering).
Pandora gives you the name of the every song it plays, along with the artist and the album information so if you hear something you like, you know exactly what it is and where to find it again. You can save your selections too, so you can listen to these "radio stations" based on your favorites whenever you use Pandora with out reloading the info.
We've used Pandora at dinner parties, and it has turned into a good time as guests suggest their favorites and we all see what Pandora comes up with.
And its free! Check it out at www.pandora.com.