Well, we have some games that keep some people coming back every day. One of them is the "One Word Game." I started a thread with one word and asked them to reply with one word that relates to the word posted above it. For example:
Peanut
Jimmy Carter (Proper names are okay)
President
War
Iraq
etc.
Each one is a reply from a different user.
Another game is the continuous story we write together. It's a fictional story and anything goes as long as a 9 year old would be allowed to read it.