Currently I am doing my civillian service in Austria (though only 1.5 months to go), but in summer when I had a little free time I built something small and neat: Colorillo.
Colorillo is a very simple drawing program on a web site. What makes it particularly fun is that you can draw together with other people. Whatever someone draws on the page you are currently on, you will see right away.
Colorillo makes use of a plethora of interesting technologies to accomplish simultaneous drawing. Among them are:
Then in October I got the chance to bring Colorillo onto the LED wall of the archdiploma 2009 exhibition at Kunsthalle Vienna, so at the moment you can stand in front of the building and use Colorillo to draw on it. It's fun!