> So what other industries do you know of that buy ideas? I can't think of any other than the book industry...

It seems that the time is ripe for a digital, networked app equivalent to be replacing books as a medium for ideas... something like Amazon's kindle library, but more revolutionary (as opposed to evolutionary).

Lots of industries buy ideas... They just prefer to do it in the "protected" form of purchasing / licensing patents.

"So what other industries do you know of that buy ideas?"

It depends on how you define an idea.

Toy and game makers.

very few buy ideas anymore, they prefer to have the people create a company proving that the idea is viable/valuable then they buy it out