Outlook? Can add into your calendar, have reminders, invite other people, add notes. it's free (to some extent) as opposed to monthly subscriptions to web applications. However you cant access it from like..any computer. It'd obviously ahve to be your machine/phone with outlook set up.
I hate outlook, im trying to learn to love it. :-/
Wish it had more "project management" features, with task lists, progress bars, etc.