I've had a rather large Address Book contact list that over the years have been synced by multiple services and some of the birthdays show a wrong year. This hint shows how you can do a quick(er) clean up of your birthdays calendar.
Users of Filemaker's Bento know that beyond being a practical personal database it is also an awesome quick editor for Address Book. In Bento, all of your Address Book fields can be shown in a database/spreadsheet format and you can quickly filter and order your contacts based on the field.
- Launch Bento (even the trial version will work), lookup Address Book and enable the 'Birthday' field.
- The hint here is that all of the Birthdays without a year in iCal are actually dated the year '1604.' So browse at your leisure and by selecting the 'Birthdays' column you will be able to see the ones which show a wrong year and change it to '1604.'
- As a result your updated Birthdays will show no years in iCal.
[crarko adds: I haven't tested this one.]

