I just saw this posted on usenet, got me to trying different things. Kind of fun:
Open Image
Duplicate Background layer
Convert to Grayscale
* Image > Adjustments > Desaturate -or-
* Image > Adjustments > Channel Mixer (set to Monochrome)
Duplicate BW layer
Invert Duplicate Layer (Ctrl + I)
Set Duplciate Layer mode to Dodge - should go white
Experiment with one of the following:
* Gaussian Blur
* Motion Blur
* Noise > Dust and Scratches
Optional: Copy Background again and move to the top of the layer stack. Experiment with blend modes.
(thanks to lmulli)
I tried other filters besides these. Unpredictable, but like I said, fun
