Okay, so Pandora is amazing, right? Not the figure from Greek mythology, the .com, I mean. It's amazing that you can create these stations that let you both enjoy what you know AND discover analogous music that you're likely to love as well. It's amazing technology.
EXCEPT! What makes it really amazing has nothing to do with technology. In order to create these analogies, these connections between songs and artists, in order to associate The Decemberists with The Mountain Goats, HUMANS (you remember them) had to go through and attach adjectives to the songs in a vast and highly discipled tree of descriptors.
If you love Pandora, don't thank the programmers, thank the librarians. Thanks librarians!