i got around to trying the Quake 1 dreamcast port, and at 320x240 it runs pretty flawlessly. considering its open source and probably not that hard to port using Windows CE, and modem initialization and networking sample code and documentation is plentiful in the WCE SDK, making the port might only take a few weeks
8 player quake 1 matches with keyboard and mouse over 56k would be pretty amazing
if someone decides to do this i nominate microphone support also for the ultimate nerd experience