It's my DS's birthday on Christmas Day. We try desperately to make it a special day for him. Christmas in the morning, birthday in the afternoon.
Have birthday banners up for when he comes downstairs. I insist that all birthday presents are wrapped in birthday wrap or they go in the Christmas pile.
He thinks he is lucky as he actually gets a birthday card and present off of Father Christmas too, and no-one else he knows gets an extra present
Mind you don't know how much longer we can carry this on being he is 8 this year, he's not admitted to not believing ... yet!
He also got a Christmas present off the hospital when he was born 
We've always said, if he wants a party he can have one in June, like a half birthday. All his school friends should be available and the chances are the weather will be better.
He's not mentioned the fact that he never gets Birthday cards delivered by the postman yet, although it's something that's crossed my mind.
My birthday, although not at Christmas, is one day before my sisters - although we are three years apart. WE used to get joint presents and cards. And parties when children [still bitter] I deliberately celebrated my 18th as the parents thought it would be a good idea to have joint 18th and 21st party. Nope, my birthday is my birthday.