The Toyota i-Real electric personal vehicle was recently unveiled to the masses at the 2012 Beijing International Automotive Exhibition, and there was no release date nor more importantly, a price point attached to it as at press time.
RYNO Motors' single-wheeled electric scooter is self-balancing, has a turning radius of zero when stopped, & only takes up about as much space as a folding bicycle -- so it's conceivable that commuters could bring one onto a train.
This concept painting of a "mono-scoot" personal transportation device was done by Richard H. Arbib in It is featured in the excellent book Driving Through Futures Past by the Petersen Automotive Museum.
Electric 3 Wheel Mobile Icona has developed the a highly innovative proposal for an emerging class of new vehicles: the Personal Mobility Vehicle. The is combining a car safety and comfort with the driving excitement and maneuverability of a motorcycle .