I don't know if you can sell this--would anyone pay? I think replicating smells would be a huge difficulty.

In a similar vein, however, I wonder if anyone has ever adapted a mass-spectrometer or similar device to recognize the smells of things and put it on a display.

Where-as my wife seems to have an exceptional olfactory system, I often can't smell anything, or I may smell something and not be able to associate what I'm smelling. Also, when you have a 'bad smell' in the house, this smeller-appliance could register the 'amount' of smell and help you find it's source.