Take the segway concept and adapt it for health-conscious people who are not afraid to put in some effort, and you have the Zingsniuoklis.
Designer Regimantas Vegele has come up with this innovative transportation/sport device as a project at Vilnius Academy of Fine Art.
The futuristic looking Zingsniuoklis allows you to get the workout you need via its walking exercise while transporting you around. It's almost like a moving elliptical machine. You move as you pedal.
I think it's a nice concept. You can use it for short-distance trips, lose a few calories, and avoid paying for gas!
For a motorized unicycle, check out the Uno: