Peter Locke created a set of colored magnets called Motifo that act as giant pixels to turn your fridge into a works of art:
Each mosaic design has been specially crafted to use the same combination of pieces, so every mosaic can be made with the 1296 pieces included in each motifo pack. If you want to create a new design, just rearrange the pieces.
If I'm not afraid that they'd swallow the small pieces outright, this would be a blast for my kids! Link - via Funfurde
I think not enough kids are dropped on their head, nothing teaches better then a bad experience.
On a side note, when I first saw the image for some reason I thought of this.
Seriously, if you have enough time to do this, you shouldn't have kids.
I would love to meet this Peter Locke, and talk mosaics. Gimme a call, Pete!