Dificulty: begginers
Software: Adobe Photoshop CS4
Plugins,actions resources: no. Some textures were used.

In this tutorial we'll learn how to draw from the scratch a strange yin and yang like cosmic object against a nebulae cosmic dust background. Here is what will be the final result:

Tutorial is organized in steps, each step will contain the description of actions taken, and the result you should get. All work was done in Adobe Photoshop CS4, and I assume that you have some intermediate knowledge of working with Photoshop. Some textures were used, I'll show you at the right step. So here we go:

Step 1.
Open a new file. Set colors to black both for foreground and background. We'll set image dimensions to 1600x1200 pixels, at 72 pixels/inch resolution in order to fit as wallpaper on your desktop computer. We'll start with drawing of the geometric form of yin yang shape. First we'll draw a ring, then specific curved inner shape.
Draw a selection in the middle of your picture:
Eliptical Marquee Tool with Shift Key pressed for simetrical dimension. Save that selection (Select->Save Selection, New Channel checked) under the name, say outside. Transform existing selection ( Select->Transform selection ) with say 90% both horizontal and vertical. Save transformed selection under the name inside.
Clear all selections (Select -> Deselect) , then load selection outside, and then load again selection inside and be sure to have Substract from selection button checked.
Now you should have a ring shape selection. Make a new layer , (Layer->new Layer or Shift+Ctrl+N), set the foreground color to white and fill the selection. You shold have this picture:

Name this new layer yin yang ring.
Now lets's draw the specific yin yang curved shape. You can do it free by using Pen Tool and adjust the simmetricity and curvature by hand, or for more accurate shape, use this technique:
Find the picture middle point by setting new vertical and horizontal guides to the middle of width and height of image.
Position the center of the yin yang ring level at the intersection of these guides
Duplicate this level. (right click on it, in the layers panel) Name it as yin yang inside, fill the ring with a different color (say red). Draw a circle selection with diamater as half of the white ring radius, and set it's position with the center on ring diameter, in the middle. Save this selection under the name half. Here is the picture:

Ok, now do Cut on the yin yang inside level, load selection half again, shift it simetrically down , (Selection -> Transform selection) , and with the same red color, paint interior of shifted selection using Paint Bicket Tool. Remember you're on the yin yang inside layer.
Draw a circle selection, scale and position it properly, cut down inside, and you'll have the right hole in yin yang shape.
The result will be: