After reading a post about Bust magazine's Twin Peaks inspired photo shoot on Chelsea's page, I ran out to buy the magazine.
As I was skimming through it, squealing with delight, I read about an interesting website, mon.thly.info. Basically, you can sign up free of charge and put in the date of your last two or three periods, the site registers it and calculates when your next one will be and notifies you by e-mail a few days or a week before to remind you to start carrying your tampons. I have to say, this might come in handy seeing as I check my e-mail more often than my planner.
Check it out for yourself and see what you think.