If you're chronically late to all your appointments, GoTime will whip you into shape by tracking all your calendar's events, their locations, and telling you what time you need to leave based on how long it will take to get there.
I'll admit: I'm pretty slow to get out of the house, even when I know I need to be somewhere soon. GoTime keeps you on track by tracking all your iCal events that have locations, calculating the walking or driving time it'll take to get there and notifying you when it's time to leave.
You can have it notify you 5, 10 or 15 minutes before you need to leave, and it'll automatically calculate your travel time from your current location, so it always stays accurate. It'll even navigate you there using either Google Maps or Navigon with one click from inside the app.
GoTime is a $0.99 download for iOS devices only. Thanks, Stephen!