In a support context, replying to mail often requires repetitive content for a common issue. Reply With Stationery would help greatly to reduce retyping / copy-pasting.
Allow Stationery for more than just e-mail templates. Allow the same for calendar and maybe even ToDo.
My personal example for calendar is having a particular format I like to use for web meeting invitations. I just need the description / body as a boilerplate, not the invitees, time, ...