Google Calendar is simply a great calendar application, and for many of us it has become the logical choice. The only problem is that to add a new appointment you have to open the calendar. There should really be a simpler way.
And it turns out there is, in the form of an extension called Google Calendar Quick Add. All you have to do is use the Ctrl + ; keyboard shortcut to pop up this dialog:
You’ll notice that the blue link in the screenshot above shows the name of my default calendar. If you have multiple calendars you can just click on the link to switch to a different calendar.
Either way the item will be added to your calendar.
You can also use the option on the tools menu if you so choose.
The one thing you should note is that you need to be already logged into Google Calendar at some point in your browsing session, although you don’t need to keep it open.