Instead of that folded-up piece of paper, if you have a box of business cards you'll never get through, those double as wallet-sized durable scratch paper. :)
Yeah at one point I carried around 3x5" cards but the regular sheet of paper is more convenient than almost anything, and I can unfold it and use the whole area or half of a side, or whatever. Biz cards are too small for more than jotting down occasional phone numbers etc. The current problem I find is I keep losing pens and rarely have one when I need it. I just happened to be looking into keychain and wallet sized pens a couple of days ago:
