Hermione's birthday

[radius_squared at hotmail.com]

No: HPFGUIDX 29722

Hermione is almost a year older then Harry. J. K. Rowling once stated 
in a chat that Ron's birthday is March 1st, and in a 
different chat that Hermione's is on September 19th. She's not saying 
if we'll ever see them celebrate.   

I believe you can see a copy of the chat here: 
http://tww.harrypotterfun.com/transcript.shtml
about a third of the way down. 

You can see more stuff like that at 
homestead.com/wildaboutharrypotter
and click on rumors, under books. They're are a lot of bits of 
information on one page.