I host my own wall calendar. There is an annual subscription cost, but it's so cheap I don't notice. I hacked it together with thumbtack 1.0 and Bic Crystal a very long time ago. Others have used it and find the interface extremely intuitive. Localization is supported. I even have pencil support. If things become tentative, we can switch over to it seamlessly. When I have a todo item, I input it onto the day and time that works best. Highly recommended.