Feature Request:
We are trying to consolidate on just one calendaring solution. Given this, users/admins need a guide of how many vacation days they are allocated, how many they have taken, and how many they have left. In addition, if any have been unallocated in one period (say a year), then whether those are rolled over to the next period.
I guess you will need to take account of weekends (if for example a user books a solid three-week vacation, but weekends are not counted as part of holiday allocation). In addition, you need to be able to set a default holiday allocation, that can be over ridden per user.
We are made up of small and relatively unmanaged teams, but I can also see the need for work flow here, so that vacation days are authorised before going live on a calendar (perhaps a separate feature request).