Idea for Linux driver: make a protocol for sending keycodes over serial ports. #96
Description
Currently the Linux driver can remap HID keyboards/mice under /dev/input. However, it could also take input from other sources such as UART/serial ports. So if you had an Arduino that didn't have hardware USB support, you could still use it to send keycodes over the serial port and let the keyplusd driver interpret them.
This wouldn't be too practical for making a dedicated keyboard since you'd need driver installed for it to work, but it be a fun way to mess around with Arduino boards and other electronic projects.