During your college quest, you may come upon my favorite open-ended essay prompt: "Is there anything else you would like us to know?" The main place you may encounter this question is in a writing supplement, although you could interpret the Common Application's "Additional Information" section as the same thing. I would look at it that way.
This is a wide-open opportunity for you to add color to your profile, to fill in details that had no other place on your application. This is your chance to add dimension, personality, and -- yes, perhaps my favorite essay aspect -- humor, to add some attractive "entertainment" value to what usually turns out to be a sometimes sterile, even boring (or worse, grim) application.