Page Tabs / Dividers / Bookmarks
It would be great to have various snap-in page dividers for sectioning off the notebook (specifically a "Today" one so that users could mark the day's plans and necessary notes). Similar to a snap in bookmark. I have attached a picture for reference, but here is the link to the pictured product:
These would also be less likely to be damaged than the stick-on tabs I'm currently using, and the verticality would fit the design of the notebook better.