I rely on my Outlook Calendar at work a lot.
I don't usually write thing on other caledars.
I always get the Nascar Pets Calendar that Greg Biffle puts out through his foundation and hang it at work.
We have one at home hanging in the kitchen, mostly to remember when we gave the Dogs their heartworm. Sometimes I buy one, other times we get one. Right now the leading canidiate is the free one we got from Michigan International Speedway.