Not to be contrarian, but I don't want ANYTHING that's been listed so far. None of it seems necessary or even desireable to me. I have a bike that works great and comfortable clothes to wear when i ride it--everything else is more or less superfluous. I went through a gear phase, as i imagine most riders do, but it didn't last long after i realized that most go-faster stuff didn't make me go faster.
I also think you should reconsider your notion that the cycling market isn't oversaturated. At least where i live (Reno, Nev., with frequent trips to Northern California), it's WAY full. Little shops are really struggling, and even the big ones have cut back and laid people off.