It's the little calendar with the great big name!
It's difficult to imagine a scenario in which this calendar would offer a compelling alternative to a pocket calendar, but the 2008 Super Minimalist Micro Calendar Reduced appeals to my inner ten-year-old, who read and reread Alvin's Secret Code and kept cipher keys on little rolled-up pieces of paper inserted in bits of paper straws. Why? To protect those ciphers from enemy agents.
An explanation of this calendar is available from the link:
Micro Calendar (.pdf download, found via Lifehacker)