Rod Dreher revealed recently that he couldn't come up with more than six of the Ten Commandments from memory. He also pointed out the irony of this fact coming from someone who often gets on his "high horse about theological ignorance," so I won't pile on.
I've mentioned before that, while I haven't retained everything I learned at my evangelical grade school, I do recall a catchy song for remembering the U.S. presidents in order. We also performed a lot of musicals, including the popular '80s Christmas program Angels Aware.
An organization was leading a training seminar for professionals. At one point the leader asked participants to imagine themselves setting out on an adventure with only ten items in each of their packs. A few minutes later, they were told that an imagined mishap had occurred and that it was necessary to leave behind five items and keep five.