Google - Calendar
Calendar - with Google Calendar, you can see your friends' and family's schedules right next to your own; quickly add events mentioned in Gmail conversations or saved in other calendar applications; and add other interesting events that you find online. You decide who can see your calendar and which details they can view. Planning an event? You can create invitations, send reminders and keep track of RSVPs right inside Google Calendar. Organizations can promote events, too. You can set up automatic event reminders, including mobile phone notifications, and instantly bring up anything on your calendar with the built-in search tool.