Really good, for what it was.
Unfortunately it wasn't much. I hate agreeing with idiots, and I'm sure you'll have reviews from plenty of them. But a lot could be added to this.
For one, some sound. A few music tracks to choose from and the ability to turn them off would give this much more staying power. The audio portal has plenty of choices you can use for free. It would also be nice to have some pre-created backgrounds to doodle on, at least a couple appropriately psychadelic. Anything really fun to draw on. Hell, make a coloring book.
The biggest problem is that there is just not much to do, and even if you take the time to make something pretty cool, there is no way to save it or make a good copy of it (aside from the obvious screen shot). A bigger drawing area would give the user more space to play in, and you might want to consider adding a fourth variable to control the speed of the random shift, rather than just the range of the randomness.
Again, good for what it was, I'll take a look at your other stuff, perhaps I will find something else I like more. Nice flash toy.