Designer Patrik Petersson took his dirt bike and a snowmobile into a shed, played them some Yanni, and the result is the Kvant Motorbike.
Combining the important parts of each vehicle, the Kvant isn't very practical, or even possible (anyone want to weigh in on that?), but it looks cool. For concepts like this, that's what matters.
Free advice though: I'm no designer, but let's get some foot pegs on this beast, ok? [Design Blog]