WiggleGif is a $0.99 Windows 8 app which can give your images a fun animated 3D effect (click the grab for an example).
Essentially it generates multiple versions of an image and flips quickly between them, creating the illusion that foreground objects are moving from side to side. The results are saved as an animated GIF, which means they're limited to 256 colours, but should at least be viewable just about everywhere.
To make this happen you must first give WiggleGif information on the image, the objects it contains, and whether they're in the foreground or the background. Sounds complicated, but all you need to do is paint on the picture, so that foreground areas are brightest, and background areas are left dark.
If you've opened a portrait of someone looking straight into the camera, say, you might make their chin, nose and forehead the lightest (they're closest to the camera). The cheeks might be next. Then you could draw a fainter line around the outline of their face.
As you're working, a Preview window displays the 3D wiggle effect, helping you to see how well you're doing. The effect itself can be tweaked by adjusting the wiggle amount (X and Y), and its speed. Once you've finished, an Export option quickly saved the results as an animated GIF.
Producing a realistic effect isn't always easy. You'll have to choose your source images with care; ideally they should have just one or two strong foreground objects. (Picture of a fountain = good, picture of 15 people in a line at a wedding = bad).
Even if you're starting with a good picture, WiggleGif's horribly basic interface makes painting a problem. You can't see the size of the brush you're using. You can't zoom in or out for greater precision. There doesn't even seem to be an "Undo" option, if you make a mistake. And this makes it much harder to produce quality images than it should be.