Recovering from my last note, this is an opposite post, and hopefully a little more positive one. A simple, black wallpaper that shows some of the more common (and some less common) commands and what they do.
It might be an interesting twist to a dark-themed setup, or even better, as the backdrop for a transparent tiled desktop. Hmm. 😈
The only downsides, as I can see, is that stretching or squishing it to any other dimension than 1280×1024 is going to make the text somewhat difficult to read. There are ways around that though.