So, this is the ChairDesk. My dad and I started and finished it tonight, made from scratch. We just bent a bar with a Metal Bender, bolted it to my chair, then mounted a pivot-able small desk (Made of wood, also from scratch) on it.

Fancy lookin', isn't it? :D
Now you may be thinking, with a small hollow bar supporting it, it's going to be wobbly. We solved that problem by adding an extra piece of wood with an indent we sanded into it, and it holds on to the chair arm very well.

Getting in and out of the chair is simple. The entire desk pivots out from the bar, as shown:

The ergonomics are AMAZING, it's comfortable and I can move the chair around while still being able to type and move the mouse. This is especially handy since I'm using a fancy entertainment cabinet as a desk (It goes with my room so well).
Discuss, rate out of 10, and enjoy.
If anyone is willing to build one I can provide them with plans and material listings.
QuickEdit: Forgot that MrCookie mentioned "How would you create cupholders for it?" well, first off I must state that I cannot have any food or drink in my room (My dad is incredibly afraid of spills and crumbs). But, there is plenty of space under the desk where you could build your own cupholder and mount it with screws. Although it is spill-prone due to the wobblyness when the desk is pivoted out.