I'm not sure if it really was an "idea" in true sense of the word. Real contribution of Noah was to make Joel aware of his inability to spot a small but profita

I'm not sure if it really was an "idea" in true sense of the word. Real contribution of Noah was to make Joel aware of his inability to spot a small but profitable segment (no disrespect intended). If you happen to be a part of company that's on the verge of becoming a "real" company then you're bound to spot such segments ignored by high-ups given you're aware of industry trends and keeping your ear, eyes and brain open. I guess people at FogCreek must have applauded Joel for his contribution in that he listened (thought, reflected and then executed) to what an intern had to say in the first place.