Tilt shift miniatures were a bit of a fad a while back. The idea is to make real scenes look like miniatures using potatoshop, viz:
(click for uncompromisingly huge version)
Essentially, you're faking really shallow depth of field and then bumping up the saturation/lightness/curves to make things look more artificial and plasticy. Works best on overhead shots of distant subjects, and it helps to have a strong light source.
The quick and easy way to fake the DOF is to apply a quick mask, draw a reflected gradient out from the centre of where you want your sharp point of focus to be, and run the Lens Blur filter over the top.
A much better but far more time consuming way is to open an Alpha Channel and create a depth mask. Mine was quite rough-and-ready (the whole building shouldn't be in focus, f'rinstance):
Everything you want in sharp focus should be white. Then start looking for planes of focus. A tall building, say, shouldn't be significantly blurrier at the top than it is at the bottom. It's best to draw a reflected gradient for the flat ground, and then use that as a reference when working out how in-focus an object should be. When you're done drawing the alpha channel, apply a slight gaussian blur just to soften it a little, then run Lens Blur on your image, and select Alpha 1 (or whatever you named your alpha channel) on the 'depth mask' dropdown.
Once you've gotten your DOF sorted to your satisfaction, it's just a matter of playing with saturation sliders and colour curves until you're happy with it.
There are some far better examples (and a bunch of groups for them) on Flickr.
If you have a camera with an
actual tilt-shift lens, please die immediately.[/QUOTE]