Have you seen this? http://www.thisdayinmusic.com
It shows you what was #1 on the charts on the day you were born.
(Go to Birthday No.1 at the top of the site, it’s free, you don’t have to log in).
My number 1's are:
'You're So Vain' by Carly Simon in the US
'Long Haired Lover From Liverpool' by Little Jimmy Osmond in the UK
'Ben' by Michael Jacskon in Australia
Loads of other good fun music trivia on the site as well.