Lifehacker reader and designer Massimiliano liked the tiny calendars he'd seen here so much, he decided to take his own crack at designing one. His design is clever, convenient, and it folds to the size of a single business card.
The free PDF download available at his Grafish Design site has a standard calendar layout, with the weekday layout of each month stacked above and below it. In other words, if it's a Monday in February, you can trace a line with your thumb down to see what date it is and vice-versa. He's also colour-coded the months to match up with whether they end on day 30 or 31, and coded February for its own little day 28 conclusion.
Grab a free, printable PDF of Massimiliano's calendar at his site, linked below.
The small calendar 2010 (en) [Grafish Design's Blog]