Heh... the Dandelion one is rather neat, thinking outside the box.
To bad ya can't tweak the settings for the Imagination one... slow down or lock effects, lines or color, maybe throw in some random stuff as an option.
Hah, that site is great. The imagination one is one of the better ones, although I liked Fractal and Strobe as well. Strobe in particular is cool... really screws your eyes up after you look away from the screen. Good find.