Turn your picture into a puzzle
Photoshop comes with a Puzzle Filter but "not a lot of people know that" it's called - Texturizer. It's probably lurking in Filter/Other. The easiest way to make it work is to choose the Puzzle.psd file (it should be on your CD) when you click on Texture: Load Texture. Once it's loaded select the Scaling, Relief and Light Direction and say OK. That's it!
If you don't like the effect of the Puzzle.psd file you can simply draw your own (you could just scan the back of a puzzle!) and save it as a Greyscale, flattened file (mustn't have transparency). Then go to Filter/Other/Texturizer and load this file.
Be sure to check other Filters in the Filter folder, you might find some good uses for your next graphic project!