A couple of developers from the Sunlight Labs community, including one of our Great American Hackathon organizers Jessy Cowan-Sharp, managed to put together something remarkable: OpenGovTracker (source here). The site lets you see where the ideas are coming in across the various agencies from a single dashboard.
What's the synopsis? According to this it's that the American People don't have a lot of ideas. Well-- a lot of agencies are pretty low on ideas. Only 611 ideas have been proposed. Treasury only has a dozen ideas? The best the American people can do is give Social Security 10 new ideas?.