Hi Colonel Panic,
I've tried probably 70% of wm's under 1Mb.
Most minimalist wm are just wm without useless features, but they do not provide real enhancements to kde/gnome/xfce experience. I'm talking about *box, waimea, flwm.... (well, fluxbox has the "tabbed windows")
Then there are tiling wm's, which do not bother you and just get out of your way. If you're on ratpoison you know what I mean,,, There are lots of tiling window managers around:
wmii: A bit complicated to script IMO, but quite interesting because it organizes windows automagically. Different desktops are organized like tags, and windows can belong to more than 1 desktop, so you can have different tags like 'coding', 'music', 'browsing'...
ion3: tiling and tabbed wm. quite advanced too. Scriptable in lua.
evilwm: not tiling but really minimal. I like the feature to move a given window to screen corners (ctrl-alt-y (top left), ctrl-alt-u(top right), ctrl-alt-b (bottom left), ctrl-alt-n (bottom right) ). you can install it through vpackager cruxports. Not scriptable
awesome wm: inspired in dwm (a wmii clone) it's a young project but looks very promising... (it's on the repos). scriptable
ratpoison: What I'm currently using it's in the vpackager repo. The most minimal wm. really easy to script. Type in a console:
ratpoison -c "split";ratpoison -c "echo split done"
Stumpwm: it's a ratpoison clone written in lisp. scriptable in lisp too.
My ratpoisonrc and a bit more of ratpoison info on http://raimonster.googlepages.com/ratpoison
Feel free to ask anything about ratpoison
Ratpoison beeing the the most minimal of them, it just gets out of your way, and you can script it even to click somewhere in your screen. ratpoison wiki is a great source of knowledge http://ratpoison.antidesktop.net/cgi-bin/wiki
btw, if you're interested in keyboard-controlled apps, take a look at http://www.vectorlinux.com/forum2/index.php?topic=3023.0