We're huge fans of standing desks, and some people even take it further and have treadmill desks. Artist-in-residence at Autodesk's Pier 9 Robb Godshaw and Instructables Developer Will Doenlen collaborated on the design and construction of this hamster wheel desk, and put the whole thing up on Instructables so that you can build it too, and and you too can totally feel like your job is a rat race.
The hard part is evidently cutting out the rings; "precision is key to smooth operation of the wheel." They had access to a big waterjet cutter, but claim that it could be done with a hand router.
You might think it crazy to cut wood with water, but it saved us many hours of jig-making and saved a lot of wood because we could nest the parts within 1/8" of each other. Plus, the precision made for smooth rolling and perfect registration of the stacked pieces upon assembly.
It is a very clever design, with the wheel sitting on just four skateboard wheels. Some commenters suggest that it should be hooked up to a generator to power the computer, which wouldn't be too hard. There are advantages over the motorized treadmill desk; Godshaw told Huffington Post: The issues with treadmills are that you don't set your own pace, and they're not interesting as furniture."
Perhaps Godshaw should get together with David Garcia, who designed this rolling library. It might add a bit of rolling resistance but kills a few more birds with one stone.