Sunrise for iPhone is more than just a calendar app: it puts important information about your day front and centre. It syncs with Google Calendar and uses Google Maps for directions to events, knows your time zone automatically and reminds you when an event is about to start.
If Sunrise looks familiar, it's because the app was developed by the same people behind the previously mentioned email digest service of the same name. The iOS app takes things up a bit by giving you an app that syncs in real time with Google Calendar, brings in Facebook events, birthdays and other notifications (including invitations you get through Facebook), and lets you create new events and invite people.
The app understands timezones and matches your calendar and alerts up to the time where you are, even supporting plain language when adding or editing events (so "Lunch tomorrow at 11am" is correctly entered).
You can fire up the Sunrise app to see your daily list of events and appointments, the same way the email service does, but the app gives you control over the individual appointments and lets you reschedule them, contact the organiser, and even get directions via Google Maps to the event or appointment location.
You can see the weather conditions forecast for the event time right next to it in your daily view, and you can use swipe gestures to move from the daily view to weekly or monthly. Sunrise is completely free and available now in the iTunes App Store.