We surely wouldn't want to see our own faceblown up and plastered on a wall, but who wouldn't want to look at beautiful children?
At UK-based company, Better Wallpaper, you can upload images (photos or otherwise) and they'll transform them into large wallpaper sheets that you can affix anywhere you'd like just as you would regular wallpaper.
If you're worried about the image fading in a sunny spot, the company guarantees 7 years without fading by which time your kid will probably be too embarrassed to have his or her photo on the wall anyway.
Besides a photograph, you might also consider a child's favorite drawing or, if you have computer "skillz", a pattern of your own creation.
Pricing varies by size, but to give you an idea, a 4'x4' wallpaper piece is around $200.
(via Print & Pattern)