While this website has free printable coloring pages, it offers something I haven't seen before. There's a section called Picture Maker and also one called Online Colouring. In Picture Maker you are given a selection of topics, such as Pig Picture Maker, Snowman Picture Maker, Fish Picture Maker and so on. Once you click on the image you're interested in creating, you are provided with a background, and a selection of images that you drag to the background to create your own picture. They're not very complicated, but for the younger ones, it's a fun way to use the computer to create some art.
The online colouring section provides you with a black and white drawing, let's say a tiger, or a clown and below that is a palette. All you have to do is click on one of the colors, then click on the section of the drawing to color it. It's an excellent way to build dexterity with the mouse. You have to be careful though, the clear button clears the entire page of color, not just the color you just painted. I also couldn't find any way to change the colors I already placed, but perhaps that's because you can't do that with actual crayons either. Regardless, once you've finished coloring your masterpiece, you can print it out as well. The site is based in England, so you can use this opportunity to explain to your child the difference in the spelling of the word color.