Segway So passé Apparently even the hallowed Harrods agrees that 2015 is high time to hang up the skateboards and scooters in reinventing the wheel &mdash with an Airwheel, a high-tech unicycle controlled by leaning forward or side to side. The device goes 24 miles on a single charge and hits 14mph. It can even run backwards. (from $849 on www.amazon.com, www.theairwheel.com)