Everybody uses Google Calendar (well, most people), and it's a tool many of us probably rely on every day to manage our lives, our work, and all the things we'd forget if our phones didn't remind us to do them.

Google Calendar has, then, also become a repository of highly personal information about us - our doctor appointments, our social plans, our whereabouts in general, and more. And because of that, giving a loved one or a close business associate access to our calendar only makes sense, right? After all, you want your spouse to be able to put dinner plans in your calendar or your coworker to be able to edit the location of a meeting if it should change at the last minute.