Hullabalu - Interactive stories for kids
Sitecake - Drag and drop CMS for HTML websites. It's flat file CMS so it's pretty fast.
Night Zookeeper - Help children develop storytelling skills
Anchor CMS - Free and lightweight blogging system
Hellosaurus - Interactive mobile shows kids can play, not just watch
Textpattern - Textpattern is an elegant content management system that is free, open source software.