Michigan State University have started selling licenses form their nifty Wonder Wall software which uses Flash Communication Server, MySQL and PHP to create a lovely familiar and child-friendly interface for an online forum.
This may be something to consider for the childrens’ microsite.
Wonder Walls are a breath of relief from textual discussion boards, chat, and IM. A Wonder Wall is like a bulletin board. Well suited to relatively short important and/or fun messages and images. Wonder Walls are colorful. They are spatial. Messages can be placed alongside or on top of other messages. Wonder Walls are a little goofy – when two cursors collide, we hear thunder. Kids especially love Wonder Walls. Grown up kids do too. The moderator can answer questions asynchronously, or pop in live and broadcast audio to all who are connected.
Wonder Walls are not intended to replace text-based discussion boards. Wonder Walls help build community and encourage participation in a different way. They are oriented towards fewer, more important words worthy of attaching to a bulletin board for the (password protected) group to see. Moderators create and assign many different Wonder Walls during a semester, each dedicated to a particular topic, question, or week.
For slightly more info check out their short paper from Siggraph.