The skrellm is a single process stack of system monitors which supports applying themes to match its appearance to your window manager, Gtk, or any other theme. It displays these system resource monitors on your desktop.
It is a minimal, multiplatform rewrite of gkrellm, because my distro dropped glib2 and gtk2 support, so I can't compile gkrellm any more (gtk3 rewrite is just a myth, couldn't find it on the official site), and none of the panels my DE has was as sophisticated as I'm used to with gkrellm.
I've checked multiload-ng (doesn't compile) and Conky (too bloated and doesn't compile either, couldn't set up its build env so many dependencies) which didn't work, so I had to implement my own truly lightweight version.
SKrellM is free and Open Source, licensed under GPLv3+, less than 400K single portable binary, hope you like it!
https://news.ycombinator.com/item?id=48538174
But it's multi-platform (Linux, Windows and some BSDs), more capable and even skinable so looks even cooler than this.