Made in PS7, but can probably be used in other programs.
-Make your 100 x100 base. Sharpen once.
-Duplicate your base, desaturate, and set it to Multiply 50%.
-Duplicate that layer and switch the setting to Screen.
-Duplicate your base and drag it to the top. Set to Soft Light.
-Paste this. Set to Exclusion 62%.
-Paste this. Set to Colour Burn 50%.
-Duplicate the Soft Light layer and drag it to the top.
-Paste this. Set to Soft Light 40%.
-Paste this. Set to Colour Burn.
-Paste this. Set to Soft Light.
-Make a new layer. Stamp your image onto it. Now, I have a Mac, so things are different for me. I press Shift+Option+Command+E. Yours is probably different. If you don't know how to do this on yours, go to Photoshop help.
-Desaturate that layer and set it to Soft Light.
And that's it! Hope it was easy enough.
If you have any questions, comments, etc, don't hesitate to ask.
I'd love to see what you get! =] ♥