Vizwl is a simple Qt app which accepts commands in a text protocol and draws them in a window. It solves the problem that in most languages it is really difficult to just draw something on the screen.
Currently Vizwl accepts commands over unix domain sockets but I hope to add a simple command line wrapper that allows you to just pipe the output of your program to vizwl to draw it.
These may not all be implemented yet, but this is the plan:
line 0 10 100 4 red rect 0 0 100 100 blue circle 100 100 5 frame text 40 20 "Hello World"