There are several projects I started some time ago - and there are even some I finished, at least to a point at which one could say they're somewhat useful :-). The most notable of them are probably Dizzy and Guckets.
Other stuff that is not listed here is probably on Github.
Dizzy is a graphical demo that makes you dizzy using rotating textures. It can be used as a screensaver. Visit its page
A game I created, which is about pouring water around between buckets without any method of measuring. People seem to like it. Visit its page
Other stuff, currently just a bunch of links.