When economists draw supply-demand charts, they put the independent variable (price) on the vertical axis and the dependent variable (quantity) on the horizontal, contrary to the usual practice in physics and pure mathematics. It’s surprisingly hard for me to adjust my thinking to that: causality ought to go the other way, dammit.
In the popular press, I think, the independent variable is horizontal if it is time, otherwise (e.g. in bar charts comparing several populations) usually vertical.
What other conventions are Out There?