The transportation of police
From today's wapo: Segways on patrol.
I am not sure when the over-hyped ginger became the folly of the Segway, I think they are sort of neat, if over-priced (but that comes from low demand). But somehow Segways have yet to take off. The article is an example of a niche where Segways might have an advantage, police officers on patrol. It is certainly better than having police in giant Chevy Caprices. They are also used by Maryland state police at BWI airport.
Transportation technologies need a base niche where they outperform others in order to gain traction in the market. Specialized markets like police may be what the Segway needs, though it might remain confined to its niches like airport people movers or warehouse forklifts.