Remember the Milk

A site to remind you of things. You make lists of things you don't want to forget, and it notifies you of them via email, SMS, and IMs. Also it can even show you where your tasks are located in real life and time, and lets you publish them too. Although I can see why it'd be helpful if other people got to view your errands, to avoid confusion, but it seems like your trusting people a bit to much with that.