Image courtesy of magazineart.org
Have you tried Google Calendar? I've started putting my schedule into it, but also all my to-do items and other events like birthdays. I have it set up so that ten days before a birthday, I get an email reminder to drop the card in the mail. I love being able to drag to-do items around to different days to plan out my schedule.
How do you plan your days and keep track of everything you need to do?