12. Get extra info in your calendar
In addition to your own personal appointments, Google Calendar can show you all sorts of info about the world around you. Head into Calendar's settings and click the Calendars tab at the top of the screen to get started.
Look for the link on the page labeled "Browse interesting calendars." Once you click it, you'll see a list of available add-in options, including holidays for a variety of countries, sports schedules for practically any sport and league imaginable, phases of the moon, and even all of your contacts' birthdays. You can preview what any calendar will look like and, once you're ready, add it into your setup by clicking the Subscribe link alongside it.