My MIL and father are born on the same day.
My SIL is born on the same day as my cousin and the day before my sister and OH is born the day after my sister (different years of course )
I am born 9 days after OH.
My OH and SIL are just under 12mnths apart as is myself and sister.

That's all I can think of at the moment. I am loving reading about others coincidences though