I stumbled upon this a couple of months ago.
Silk allows you to create colorful art against a stark black background. It has a really nice spacey effect. Choose your color or combination of colors, click and drag across the screen. Depending on the colors you chose and the pace of your stroke different, tiny silken strands of color escape from your mouse and create flowing art. Careful not to go to this site if you have other things to do because you will get distracted.
Here are some of my silk creations.