If you're a GTD devotee, or just a regular user of a pocket briefcase (as I am) or a Hipster PDA, then you'll dig this recent discovery. Mead makes a half-sized index card. They're 3 x 2.5 inches (7.6 x 6.3 cm) and I'm finding them quite handy. They're easy to carry, and perfect for a short note. They also fit quite well in a regular wallet; right up next to your credit card and bus pass. A packet of 200 is cheap at Office Depot, but despite my best search-fu efforts, I can't find them listed on any shopping site. But, they do exist, so go forth and seek.