I talked to a guy some years ago, and he wanted to do a sort of serial device thingy that, instead of using the serial port, did some TCP/IP thing, so Serial communications were emulated.
Don't know if he ever got it working, but the idea is great, if it could work, then games like stuntcar racer could be played via internet.
Hmmm any one up for the challenge of doing such a device ??