With Outlook 2013 you can easily get a preview of your upcoming appointments on your calendar, tasks, and more. While checking your email, just hover your cursor over Calendar at the bottom and a small pop up calendar will appear with your upcoming appointments. Click on any of the days on the preview calendar to see the appointments you have set for that day.
You can also hover over People and Tasks to get a “peek” at them too. Then just click on an item in Tasks, Calendar, or People to open it.