When Thea Spyer died in 2009, she left all of her property to Windsor, including the apartment they shared. Because they were married, Spyer's estate normally would have passed to her spouse without any estate tax. But because DOMA prevents recognition of the otherwise valid marriages of same-sex couples, Windsor had to pay more than $363,000 in federal estate taxes.
Some people seem to think "those people" are just whining about this "imaginary" discrimination. Can't get much realer than $363K of extra taxes.