Not really. There are a some work arounds but a calender is something that has been requested for years and is on The List. If you would like to keep a to do list you can add a rich text widget to your home page. You can edit it to change your information as often as you would like. The other (not so great idea) is to create a private group just for you. I use one to keep all kinds of CafeMom content for easy access at CafeMom. You can use the calendar in that group for all kinds of planning of events and can arrange to receive email alerts from it as well.
You can also join the requesters for a calendar widget by sending a contact us report from the link at the bottom of any page.