I have our calendar in it of course!
I also found those handy dandy post-it tabs and have marked other sections like meals and day pages that have a list of what we are hoping to accomplish each day.
I even have a school section for activities, our school year calendar and the current years curriculum for each child.
I put most things in page protectors so they don't rip or get sticky fingers on them. I keep the notebook open, on the end of my kitchen counter. When I want it out of the way I will stand it up and tuck it back under the cupboards against the back-splash. As of the last few weeks it hasn't left the counter. I finally figured out how to use it in a way that is helpful to me. I love that it's a 3 ring binder so I can add to it and it has truly become "my brain" at times. You of course can do this with just a plain ol' notebook but I love the pockets and extras that came with this one... and it's prettier than a plain ol' notebook which makes me more apt to use it! Sad to say but true.