From David Andrade
Google Calendar is one of Google's many free resources that I use. It has some features that make it very useful.
It's accessible on any web browser and integrates and syncs with smartphones, Outlook, Apple iCal and Mozilla Sunbird.
I have all of my appointments, due dates, deadlines, etc. on it. I color code them based on school, blog, degree program, meetings, fun, etc. My wife and I share our Google Calendar's with each other so we can easily see each other's schedules. If you use Google Tasks and set a due date for the task, it will show up on your calendar for that day. I also have US holidays and the Yankees schedule on my calendar.
Via Susan Bainbridge