Over on the Color Computer mailing list, Frank Swygert (editor of American Motors Cars Magazine) mentioned a project where someone else was using a Teensy to hook an old matrix-style keyboard up to a modern PC.

A bit of Googling led me to a similar project where someone built a Radio Shack TRS-80 Model 100 keyboard interface that lets you use it on a PC via USB. This is precisely one of the things I will be doing with a Radio Shack Color Computer keyboard (also planned to use the Teensy 2.0, since it has enough I/O lines and is very inexpensive). Share and enjoy:

http://www.seanet.com/~karllunt/M100_usb_keyboard.html

I have also been informed that Chris Hawks of HawkSoft has already done this, using a Raspberry Pi running a version of the MESS emulator. He created a scaled down version of MESS to emulate the Radio Shack Color Computer, then used Teensy to interface an actual CoCo keyboard to the Pi. Very cool.