Orton imagery, also called an Orton slide sandwich, is a photography technique which blends two completely different photos of the same scene, resulting in a distinctive mix of high and low detail areas within the same photo. It was originated by photographer Michael Orton.
The original technique [...] was to overlay two or more images of an identical scene with very different exposures on slide film. One image is sharply focused and the others are very out of focus.
I followed this tutorial, with mixed results. The amount of gaussian blur really seems to make a difference and I haven't found any kind of formula, other than playing around, that gets the best results.
But when it's right, it's great. It's almost a watercolour or impressionist type effect, and I'll definitely experiment more with this one.
The tutorial is written for Elements 5, but it works fine on Photoshop CS3.
Other of my attempts are here and here.