Get people together easily - Just pick a time (based on when people are free) and enter meeting details. Google Calendar will send invitations and keep track of RSVPs.
 

Share project calendars - Share whole calendars company-wide or with specific people. Coworkers can have editing rights and see shared events alongside their own schedules.
 

Show event information in context - Embed an internal calendar in Google Sites or publicly on your website, no programming required.
 

Interoperability - Sync your Microsoft Outlook calendar with Google Calendar