Spore.

http://www.pqhp.com/cmp/gdctv/
Video near bottom, you should probably use a spamfilter-address for the registration process.
This game looks like awesome.
Will Wright is actually funny?

You probably have control over what you download. I'm guessing there will be some kind of "content browser" built into the game. That may even be what the additional buttons were for.

tl;dr version

PUSH BUTTON RECEIVE CONTENT