Make and cancel appointments (Future appointments and Walk-ins)
Check-in and undo check-in's.
No-show and undo No-shows.
Make slots (i.e. how many patients will a provider see)
Set Overbook permissions to Clerks
Print Schedule List for Providers
Print Appointment List for Patients
Print Appointment Reminder Letters
Auto-Rebook appointments (along with Rebook letters)
Search for appointments in the future (you can limit to specific slot type or day)
Integration with the Radiology Package to make Radiology Appointments (v 1.6)
Dynamic view of Schedules:
Can open multiple schedules for a Clinic Group
Can view a single schedule in 1, 5 or 7 day view
Can change the time scale as long as it isn't less the minimum appointment length 
Bi-directional communication with PIMS Scheduling Module.
Appointment Clipboard Functionality
Drag and drop for appointments
Full UTF-8 support if the Mumps Database supports it.
L18N for Arabic