Hardware companies have tried to improve the mousing experience ever since Xerox Parc developed the modern Gui WIMP and Douglas Engelbart invented the mouse. Scroll wheels, optical tracking, trackballs, and cordless operation are among the more popular, and useful, improvements. However, all of those improvements still confine the user to a horizontal plane. It would often be nice to sit back and casually thumb the mouse around without staying on the table top. Imagine how much more comfortable marathon web sessions would be.
The design of the the Nintendo 64 controller allows for such an experience. The pistol grip allows easy mouse movement with an analog thumb switch, and left-clicking is directly under your trigger finger. There's even a bevy of accessible buttons ready to handle less-used actions, such as middle or right clicking. The only problem is figuring out how to get a Nintendo 64 controller to pretend it's a mouse and talk to a computer.