Are you busy? Well duh—who isn't? With a full schedule to stay on top of, it's easy to get confused and show up for meetings an hour late, or make important phone calls an hour early. If you're not sitting at your desk, your calendar probably isn't available to you. Reminders on Outlook are only useful if you're sitting there watching them pop up.
MemJog is a free service that sends reminders to your mobile phone. Create an account, make sure your phone works with the service, and start entering reminders. Now you've got no excuse for missing important events.
While they include a lot of cellular carriers in their list of supported systems, they don't include everybody (Virgin Mobile is missing), and they're not completely up to date (they're still talking about Cingular).
While MemJog is free, remember that you carrier may charge you for SMS text messages.