I've been using cmus as my music player on Linux lately. It's neat, I love it, but I have trouble remembering some of the controls and commands. I went looking for a cheat sheet for it, and I found a couple on Cheatography.
Not only did they have cheat sheets, you can easily create your own. The existing cheat sheets for cmus probably suited their creators, but I have other needs. So I signed up and started building my own. This is a really neat site. I've got most of the info in my own cmus cheat sheet, but I'm not done yet, so I haven't published it. I'll probably have it done this weekend and I'll add it here.
In the meantime, it looks a bit like this:
I finished it and published it. You can download the cmus Cheat Sheet from Cheatography. As time goes by, I will tweak it and maybe add some stuff to it.