People sometimes ask me where they can find a list of special days on the calendar. Sometimes they want to know about the more unusual or silly dates, like "National Ice Cream Month" or "Hug a Geek" day, and other times they want to know when Easter falls this year, for example. Being aware of those special, silly, serious, and official holidays can help you plan out your time with friends.
They're also a good way to keep in touch. For example, if you're looking for something to write on a friend's wall, you could always check for a special holiday and write "Happy Backwards Day" on their Facebook wall or in an email. (Or maybe I should say, "Yad Sdrawkcab Yppah"?)
I've got collection special calendar days here. You can use them to personalize your friendship calendar, day planner, or more. Enjoy.