A great web-based tool or creating your own printable calendar is available at http://printable-calendar.co/#/, and is very easy to use. You simply select the relevant month, click on the day and type in whatever you wish to add to the calendar. When you are finished, you simply click the print button, and you then have a printed copy of your calendar. You do not need to log on, create a user account. This makes this quite a powerful classroom management or lesson planning tool. By printing to pdf you can then save the calendar so that it can be emailed to students.
You cannot save the calendar on the website, so applications are limited, but it is a useful way, nonetheless, to remind students of homework or test schedules, record your own lesson plans, or set up meeting schedules. I find it very useful for creating monthly schedules, which I then post in pdf form to the class Moodle page.