I used to have three planners, and they looked like this:
1. School Agenda Book - Extremely important, but also highly work based. It has things like days off, meetings, and lesson plans. It's so valuable I even keep the previous year's version around for ideas.
2. Google Calendar - Fancy and digital! In this I note days off, some meetings, appointments, and certain very important social events (usually far off in the future, like weddings).
3. Personal Planner - A small thing, I used it to write days off, certain meetings, appointments, and also cryptic markings that designated my menstrual cycles.
After a while genius me thought, why are you writing the same things in multiple planners? Streamline! And I toyed with this idea for a while until I remembered a site I had seen this menstruation tracking website, mon.thly info. And that solved the whole But how will I know when my period is coming? problem. I like this place: it's pretty and pink and it keeps track of lady business way better than pen and paper can, with standard deviations, predicted ovulation dates and lots of other cool stats. [Note: all of these stats are useless if you're on the pill or the ring or anything else, which makes me sad.] In fact, it's so great that I'm upset that my quick stint on birth control completely ruined my cycles and averages. But hey, I'm not pregnant.
Anyway, long story short: natural hormones are pretty neat. Digital planners are nice. And if you take my work agenda book away from me, I will cry (possibly more when I'm hormonal).