Evilwm is a minimalist window manager for the X Window System. It is based on aewm, which is based on 9wm, which is based on 8 1/2. It is easy to set up and use, and has few weaknesses, so long as you know Unix and X pretty well and like the command line. In other words, this is definitely a minimalist Unix geek's window manager.
As features go, Evilwm has window resizing, movement, multiple desktops, and not a lot else. The only real visual provided is a 1 pixel border on each window, which dissappears when windows are minimized. There is also minimal information provided when resizing or moving a window, or when you press ctrl-alt-i for window information. You can't change the color of the border or the windows, but I wouldn't bother anyway.
The controls are simple. There are a few keyboard commands beginning with CTRL-ALT to move, maximize, and change windows; change and transparently create desktops; and pin windows. There are also mouse commands for moving and resizing windows. (ALT-BUTTON1/2/3. You can also use the 1 pixel border, but it's very annoying.) There is one last, essential command; pressing CTRL-ALT-ENTER opens up a terminal, so you can run programs. The interface sounds small but it really is nice and clean.
That's all there is to evilwm. Anything else you can do with it is because of the X Window System. Dockapps can be run without too much annoyance by moving them to a corner (CTRL-ALT y/u/b/n) and pinning them (CTRL-ALT-f). It might be instructive to play with Xnest along these lines. You can mess with xsetroot if you want a background color, or hsetroot if you want an image background.
Evilwm is a great window manager, but I started using Evilwm so I could look at the source code. A few hundred lines of code do all the work; the entire source code, a whopping 5 or 6 files, can be understood by a beginner (such as myself) in a matter of a few hours. It is instructive with regard to writing window managers and use of Xlib. Start with 'evilwm.h' if you're going to have a go at it. Note that the author suggests looking at aewm also.
Installation: If you're running Debian, a simple "apt-get install evilwm" should suffice; NetBSD users can try "pkg_add evilwm", and FreeBSD users "pkg_add -r evilwm" likewise. Otherwise, you'll probably want download the source yourself. I wouldn't bother with changing your .xession or .xinitrc file; just start a failsafe session and run "evilwm &", and then exit the shell when you're done.
There are many window managers related to evilwm, many directly based on it. Rather than list short-lived projects, I advise you to Google for the phrase "based on evilwm".