Kiddix Computing has come up with a Linux-based operating system designed especially for children aged 5-10. All of the icons for applications are situated around the edge of the desktop. There's e-mail, a browser, an office suite, a paint program and some games (both educational and just plain fun). All are built with open-source code, and everything has a user interface designed for kids. You can test it out with a Flash demo at Kiddix's site.