Google Calendar Chrome Extension adds a button to your browser toolbar that displays a preview of your calendar while you're navigating. (works on any page). If you're on certain sites where it detects the presence of events, the icon changes to a green "+". Clicking that icon lets you add the event to your Google Calendar, and shows you a Map (if there's a location it could detect.) Supported sites include Facebook, Evite, and any site that uses the hCalendar microformat or derivative microformats such as hResume.