If you'd like, you can set your birthday in the UCP (User Control Panel, link at the top left of the page). Hit the UCP, then the Profile link on the left. Birthdays are set at the bottom of that page- Day/month/year format. You don't need to set the year if you don't want. After you do that, your birthday will show up at the bottom of the index page when it's your birthday.
Sweeeeet!
Happy Birthday.