The Wittig Oszifox is a small, cheap, pen-type oscilloscope made by Wittig of Germany. It has a tiny screen built in to it, but I wanted a larger one. This page describes the protocol. The display program just display - the protocol is one way, so there's nothing for the program to do except sit there and draw what it gets.
Download the source.
goszifox works on FreeBSD, and should also work on Linux. It opens
a 1024x768 window, then listens on the serial port (specified with
/dev/cuaa0). I run it full
screen on a dedicated monitor next to my workbench.