We have a number of companies who use Office 365 Kiosk plans for their remote staff, seasonal staff, or plant floor staff. Just because they are Kiosk users does not mean they have less of a need to collaborate. Sharing your calendar is insanely easy in OWA – probably even easier that the Outlook rich client just because it’s easier to find.
Go to the Calendar portion of your Office 365 portal and look to the right hand side. You will see the “share” button. If you click that button you will be able to easily share your calendar just by typing in the email address of the person with whom you want to share your calendar.