The mechanical engineering students at Yale came up with a novel bicycle design, featuring a spokeless rear wheel.
I don't imagine it will become the default setup any time in the future, but it's interesting. (The mechanicals residing underneath that upper plate that holds the rear wheel in place? I imagine they add considerable "rolling resistance.")
When you think about it, the "traditional" double-triangle bicycle frame design has been in production for well over 100 years. What other vehicle even comes close? That speaks volumes about the simplicity and elegance of the design.