I love all the ideas concepts I've seen popping up designed to help people stay active and mobile. The GlideCycle is an invention along these lines. By supporting your body weight, it allows you use your legs to push yourself along either like a scooter or with a running motion depending on your abilities.
I couldn't get any of the videos to embed properly so head over to the GlideCycle web site to see these bikes in action.
[Image captured from GlideCycle video: