This is one of the best websites for learning while having fun. There are over 6,000 printable images of everything you can imagine. All you need to supply are the crayons. They have coloring pages of some of today's most popular characters, like Spiderman, and Dora. There are pages with almost every imaginable kid's name so you're sure to find your children's.
If you have a budding art student there's also a section with simple drawing lessons, like how to draw a lobster or a starfish. One of the best activities is color by number with a twist. You have add the numbers in order to figure out what the color should be in a specific space. For example, 0 + 1 is red, 2 + 4 gets colored blue, and so on. For homeschooling it's a great way for teaching math at the same time they're coloring. They have pages appropriate for preschoolers to 10+ years of age.