I love useful posters and maps and planners. Right now, we're working on days of the week and I've printed out little wallet-photo-sized images to represent daily excursions. 

We also have a hanging wall planner, courtesy Tracey of Building My House ( http://buildingmyhouse5.blogspot.com ) that I use to keep track of snacks, appointments, and dinner meals. It also has a Bible verse on it that I change out about every two weeks.

And now I should probably go clean while the boys are happily sorting flat marbles for fun (and education!).