To demonstrate how difficult this art is to create, I decided to try it myself. I am using Photoshop 7 with NO 3RD PARTY PLUG-INS.
Source Image:
Final Image:
I used nothing but the filters included with PS 7. Once I copied the layer, rotated it 180 degrees and then merged them together.
I guess I am a super artist and I DIDN'T EVEN KNOW IT! Excuse me I'm off to charge people to use my backgrounds in their "Make a website in 5 minutes" packages.