A lot of the cards should have some kind of mark or sticker on them that says 'x' % of this cost goes toward -insert charity- I've bought charity Christmas cards a number of times, also I have bought cards made by handicapped and the money goes to the handicapped centers..
.. a little research and you'll find deserving ones but let that be a lesson not to buy the first one you grab.
"I have always thought of Christmas time, when it has come round, as a good time; a kind, forgiving, charitable time; the only time I know of, in the long calendar of the year, when men and women seem by one consent to open their shut-up hearts freely, and to think of people below them as if they really were fellow passengers to the grave, and not another race of creatures bound on other journeys." ~Charles Dickens