I saw these photographs the other day and I keep thinking about them. They were taken by Alejandro Guijarro, and it's a series called Momentum.
He took pictures of physicists' blackboards from around the country, and they look really neat:
I really like it when professors use the chalkboard or white board to teach classes. I find myself much more engaged in class compared to when I am shown yet another PowerPoint slide. I feel that only time PowerPoint is appropriate to use is to show pictures or animations, not paragraphs of text. I hate it when professors read paragraphs of texts off of their PowerPoint slides.
You should look at the rest of the blackboard photographs--they're really cool. Also, they're bigger on his website, so they look better too.