Well, we didn't make this calendar, but we did print the PDF that we bought from Mibo for a whopping $4. We have one hanging in our house, and we gave a bunch away at Christmas. Other than the pom poms, this was the only DIY project I took on for the holidays.
Benign Objects has designed a free 2010 calendar too. I didn't print that one, but I do use the free computer desktop calendars from that blog, on occasion. Since we're on the topic, Design*Sponge offers free desktop calendars too, like this lovely January calendar by Julia Rothman:
The desktop calendars are a welcome sight when I turn on my work computer, especially because I haven't made too many efforts to personalize my office space.
I love this trend of offering free or low-cost files to download for personal use, especially because it's not limited to calendars. Twig & Thistle recently offered a PDF for these Valentines Day treat bags, and I've noticed a few PDFs for bookplates and prints on Etsy. Fun!