Google Calendar (Gcal)
It is one of the best calander applications available. Adding daily schedules is as easy as typing "Outpatient - Mr. John Smith at 3 to 3:30 pm today." Gcal also provides a form for more detailed data entry including reminders (via email or phone text message). It also allows invitations, RSVP and guest comments.
However the most powerful features of Gcal is that it supports multiple calanders with the ability to share individual calanders with different people. For instance a calander could be setup to show patients the time that you (the doctor) will be available in the outpatient setting so that they can schedule their visits accordingly. Another calander could be created and shared only with colleagues outling the meetings scheduled for everyone.
Since Gcal supports the open source calander protocol, thousands of calanders available on the internet can be imported into your calander. Examples of such calanders include list of holidays by country or religion and sports schedules.
Gcal integrates with Gmail beautifully with the ability to create events from individual emails. Gmail will also automagically recognize meetings and events in emails and offer a link to add them to Gcal.
Google Calendar overview
Google Calendar tour
Video Tutorial
Interesting Links:
1. Google Calendar for Patients: Monitor Your Medical Condition
2. Google Calendar for Doctors: Help Patients See Your Practice Schedule and Make Appointments