There's been some discussion at Metafilter about using your calendar to remind yourself of recurring events. I have been doing that already for the last two years. I use my calendar to remind myself of tasks ranging from the mundane daily stuff to weekly and yearly actions.
Here's a sampling of some reminders:
Daily - check weather, take vitamins, sit up straight, drink water, fill out worklog/daily checklist/timecard
Multiple times weekly - go to gym
Once a week - seminar reminders, listen to new music, backup hard drive, replenish cash in wallet from ATM, update financial information
Once a month - more extensive computer maintenance, clean room, clean bathroom , change contact lenses, go over finances
Less frequent - birthdays, reminder to send Christmas cards, quarterly review, reminder to write an update to stay in touch with friends
My view is that my calendar is a gentler version of the nagging mom. Maybe one of these days I will finally sit up straight!