I've put together a calendar with some important family events.
It's a google calendar, so if you have a gmail account you can add it to your existing calendars by pressing the '+ Google Calendar' button at the bottom of the calendar here. Once added to your email account, you can synch all the birthdays and other important family events right to your smartphone.
If you want to be able to add events, send me an email and I give you the permission: firstname.lastname@example.org.
*UPDATE* I've added the email addresses of everybody who contributes to this blog with the permissions to add/edit/view and also grant permissions to others.