I try to keenly watch for concise, potent, info dense stuff that I can put on such cards. I spend a lot of time at this but not unlimited time.
I look for such things due to a lifetime list of people with whom I correspond. The old fashioned way, through the postal service. I developed the habit years ago of including an extra in every card and letter. I've used colorful index cards printed with scripture, quotes or short verse.
Good information packed facts as you suggest passing out personally are a welcome new twist for me to add as my extra. I know some of my correspondees probably throw my cards away but I've observed them on refrigerators, used as bookmarks, sitting on desks or tacked on walls so I know some are meaningful. Probably shows my age using snail mail and the pre-internet form of meme.