I was thinking about the same thing.
With all the new mini projectors coming up, an app for writing, saving and editing whiteboards into digital documents will be a guaranteed winner.
You get a brainfart for a revolutionary new type of fork/knife, that cuts food into bite size pieces, holds it, and scoops up gravy.
You draw scetches of it on paper or a board, write some and scan it on your phone.
Then 4 days later brainstorming class putting a phone in a coffe cup, and firing up a evernote whiteboard app. You direct the phone torvards a white board, and the projector displays your sketch . You can edit it, turn the writing into digital text.
Then you share it with your dev team. make and share 3D models, and print it on a 3D printer.