Can select the type of image then color it in without the need to print. So not need to stay within the lines
Yet another, but it has sounds
If you chose to color online you can do so outside of the lines with this one.
If you use this one more that a certain number of times you have have to pay to continue using it:
Scratch. Bit more than a coloring in sim, as you can create your own drawing and animate them as well
Scratch is a project of the Lifelong Kindergarten Group at the MIT Media Lab. It is provided free of charge.