This is one of the best xwindows/xorg windows managers ever made. I use this on all my work stations because of its awesome features which include.
* Configurable window tabs.
* Iconbar (for minimized/iconified windows)
* Wheel scroll changes workspace
* Configurable titlebar (placement of buttons, new buttons etc)
* KDE support
* New native integrated keygrabber
* Maximize over slit option
* Partial GNOME support
* Extended Window Manager Hints support
* Slit dockap ordering
* Other minor features
The feature that I use most often are the window tabs, which allow grouping and fast switching like the TabMix Plus extension for FireFox. And the key binding configuration, which is relatively easy to use. Once you have fluxbox configured, it will drastically increase your productivity.