Here's a tutorial on how to do a nice looking orb looking like this:
http://www.deviantart.com/deviation/29528490/
Ok so let's start.
1) Open a 400 x 400 document in photoshop with white background.
2) Set your foreground color to black, and background color to white.
3) Do Filter > Render > Clouds
4) Now Filter > Render > Difference Clouds
5) Repeat step 4 for about 7 times. Tip: Press Cntrl + F.
6) Now go Filter > Distort > Twirl and enter 387.
7) Now Filter > Distort > Pinch and enter -100.
8) Repeat step 7.
9) Ok now go to Filter > Distort > Polar Coordinates and select Rectangular to Polar.
10) If you noticed, it doesn't look good at the top. So let's select that part with the Rectangular Marque tool. Like this:
11) With that part selected, go to Filter > Blur > Motion Blur to fix the colors. Enter 0 in "Angle" and 33 pixels in distance.
12) Now deselect. You will notice it still doesn't look good, so let's fix it. Make a little bit larger selection to get the whole rectangle. Like this:
13) With that part selected, go to Filter > Blur > Gaussian Blur. Enter about 1.4 pixels. You may enter more if you wish.
14) Now, it definitely needs some color. Go to Layer > New Adjustment Layer > Color Balance. It will open a new box with some settings. Play with those settings until you have the color you need.
15) Voila! You're finished!
If you wish to make this orb your wallpaper, go to Image > Image Size.. and enter 1024 x 768. If it looks bad, repeat the whole tutorial but with 1024 x 768 image size and larger filter effects (entering more pixels).
Hope you like this tutorial, enjoy!
Tutorial by
zCE (me).