And another link for an activity my family does all the time with flour to learn about the moon's craters: http://blog.growingwithscience.com/2010/12/weekend-science-fun-lunar-eclipse-coming/
Additionally, make moon desserts like cookies (healthy if possible), sing songs about the moon, and read books about the moon! Once we made a raw crescent moon cake using a healthy macaroon recipe. Delish.
Finally, I got a bunch of ideas years ago from the book "Jewish Everyday: A Complete Handbook for Early Childhood Teachers" by Maxine Segal Handelman. That book is just a great resource on all levels of bringing the Torah into a child's world, but specifically the Rosh Chodesh ideas are wonderful. My favorite was making a special moon spot where you go to view the moon each month. Don't forget to post what you're doing too! I'd love to know how you celebrate!