I have on my Bloglines list a site called Kiddley. The blog owners recently had a baby (the mom's blog is Weewonderfuls), so Kiddley has slowed down a bit, but is still going. Awhile back they had a post about Kids Craft Weekly, which has a theme every week and a free email of craft ideas for that theme. KCW is for the younger kids, but Kiddley itself has games and activity suggestions for kids of all ages. If you are stuck for an idea, check it out.