Among my earliest memories of using a computer are when I played with "Kid Pix" (a digital art program for kids) in my elementary school library. Craig Hickman created Kid Pix for Macs in 1989.
This classic software is now available online. Vikrum Nijjar has converted Kid Pix into a browser-friendly version. This version contains many of the old tools such as stamps, fun brushes to play with, shapes, colors, and letters. It also contains many of the sound effects from the original version. I haven't heard these sound effects since I was a young child, so It was a trip to hear them again.
Even as an adult, Kid Pix is a lot of fun to play with. I spent about an hour drawing on it before I finally settled down and wrote this post.