Google Calendar is a must for anyone that has any desire to stay organized. Whether you are single, or have a family, follow sports, work, attend meetings, or do anything besides sit on the couch, this tool is for you! Google Calendar lets you create appointments simply by clicking on a day, and entering the details. That's it! First step to getting organized, done! You can create recurring appointments, share your calendar, and subscribe to calendars of your favorite teams, cultural holidays, even browse interesting calendars. But wait, there's more! You can set up a calendar for each member of your family, and color code them to view all at once. I even have a calendar for the house that includes garbage and recycling pickup, house cleaning, landscaping, and even visits to the vet. If your district is using Google Apps, you can even use Google Calendar to create appointment slots, which is great for signing up for the lab, teacher edit appointments, or office hour appointments. Oh, and have I mentioned that you can sync your calendar (and everyone else's) to your smartphone? GENIUS!!!
Screenshot from the MacBook Air (Command+Shift+3--> I learned that today!)