While hunting for spray paint at Menard's, I came across this:
Eureka! Inexpensive (under $10), easy to find and apply, this was my answer. Now, I keep a can of this on hand at all times. Here is how I use it:
I lay the picture I want to spray face up in a dry, well ventilated area (my driveway). Shake the can for about 1 minute after you hear the mixing ball rolling.
(Pretty impressive pictures, right?)
Spray a light coat 6"-8" away from the paper. Wait a few minutes and apply at least one more coat (I do a total of 3).
Once dry, turn it over and repeat on the back. Paper is porous and I want my pictures to remain as close to original condition as possible.
That is it! So go round up all your little people's amazing refrigerator art and spray away!