Z80 computer
This is a small single board computer I made using Grant Searle's design. It has one serial port for communication and is programmed via BASIC.
This is the PCB I made with a small case.
links and opinions
This is a good project and very fun to make. Unfortunately I have lost the gerber files for the PCB so I cannot release them.
Grant Searle's site is here. I highly recommend that you check out his designs.