The ability to have multiple people in different states or even countries collaborate with each other.
I think it's best used when there is more than one person working together from the same office but are not physically present at the school/college campus. It has helped me manage my work schedule better by being able to plan ahead of time what activities will be happening next week. There could definitely be some improvements made such as adding scheduling options that can sync up with Google Calendar / Outlook calendar (e.g., having our weekly meetings scheduled automatically).