Creme de la Craft posted a quick way to upcycle old cereal boxes into mini notebooks. This is a great way to use up leftover paper scraps to fill or decorate. The only additional tip I would make would be to use a sewing machine and a heavyweight needle to sew up the binding or follow the traditional bookbinding method for piercing the spine and threading your string or floss for a single signature booklet.
Awesome. I use old cereal boxes all the time to make cards for my vintage and handmade jewelry to be displayed on. I never thought of making notebooks, though!