Fluxbox is a minimalistic window manager for *nix systems, based on Blackbox. You can replicate its look and feel somewhat well with complex shell replacements like Litestep, but there’s no reason to settle for that. Blackbox itself was actually ported to Windows, and there are several projects now in development based on that code. The main one you should be concerned with is bblean.
It can be a bit difficult to get everything working, and has gone a while without being updated. So, if you’re like me and you want the latest and greatest, look no further than utbox. It’s a modified version of bblean with new features and easier setup. Here’s the description from the official website:
usetools blackbox (utbox) is powerful replacement of wellknown default windows gui shell (i.e. explorer). it covers all basic explorer’s functions (and components like taskbar, system tray, start menu, right click, etc.)
and adds its own functionality , fast and smart interface and great stability of working.
by disabling explorer shell windows os (tested on win xp sp2 and 2k3 sp1) begins new life with sharp and fast features reflecting not only on gui shell enviroment but the whole os working. we call it “windows without windows”.
the main utbox idea is to provide extremly fast, tiny and stable shell for windows with the same (or more?) usabilty as common standard explorer shell has.
The program replaces explorer.exe, and in doing so speeds things up quite a bit. It generally takes up between one and two MB of RAM (!) and is highly configurable and useable, especially to those used to fluxbox.
Another very nice tool that can be combined with utbox is the ut re-source pack, which comes with a bunch of window decoration styles (among other things). When used in combination with utbox, the window decorations will match the style set by utbox.
Here you can find a bunch of Blackbox screenshots (using themes that work with bblean, utbox, and bb4win).