The best way to learn new words and phrases is to use them actively. The next-best way to learn new words is to be exposed to them as much as possible. And since the wallpaper that adorns my graphical desktop environment is what I stare at most of my waking hours, I thought that it'd only make sense to add words and phrases I want to memorize there.
Half an hour after the eureka moment, I had a working hack consisting of a plain text file with words and phrases along with their translations, a wallpaper template PNG file, and a simple Bash shell script. The latter pulls a random line from the text file, and uses the template to generate a new wallpaper with the picked line. Below are all the gory details worth knowing if you want to roll out something similar.