Umair Haque over at Bubblegeneration has a great name for sites that take individual bits of data or media and aggregate them together in a new "cast" or "stream". He calls them "reconstructors" and highlights this sort of service as a killer position in the new media value chain.
A new UK startup called Songkick is a great example of a Reconstructor - they take information about concert tickets from all the major vendors and ticket exchanges and pull them together for you. You can create your own stream based on your itunes music library or personal preferences.
Keep a look out for these guys - they are going to be BIG.