I had a card for a while. Being at one time a part of the disciplinarian industry, or prison industrial complex, it is enlightening for me to be reading Foucault's Discipline and Punish: the Birth of the Prison. He understands the theory behind the penal system and explains things in a lucid way. The translation is very good. The link has a lot of excellent reviews of the book. I read it four or five pages at a time and just sit and think about what he's saying. It's like little lightbulbs of enlightenment going off in my brain. Terry says watch out for the big ones, or I could get a stroke.
I collect cards. Here are a few I like: You can enlarge the image for a better look.