That's an easy one: The Department of Defense. A great deal of the DARPA budget is dedicated to paying companies like Intellectual Ventures, or their partners, to develop one or another of their ideas into some military technology. Moreover, companies like Intellectual Ventures would not exist if it wasn't for the fact that -- unlike consumers -- the U.S. Government is often happy to pay for ideas that have no successful implementation, and may never have one.

Do you think it's a coincidence that one of Intellectual Ventures' key employees is a former Star Wars researcher? Do you think it's a coincidence that one of their brainstorms was a way to prevent post-injury strokes in soldiers? Companies like this one don't brainstorm at random; they think towards the money, just as a plant grows toward sunlight.

It's not all military, of course: The NIH and the NSF are also good for pure-research money.