The ICE Window Manager
IceWM is a window manager which has been coded from scratch for speed and flexibility. It shares no code with other window managers. It can be Gnome-compliant and can use Imlib for graphics support.
It comes with several default themes, including Motif, GTK, OS/2 Warp (3 and 4) and Windows (95 and 3.1) looks, but the theme support allows it to be fairly flexible and it can do reasonable imitations of Mac, RiscOS, Enlightenment's Brushed Metal, AfterStep and Window Maker with the appropriate themes installed.
IceWM is extremely configurable and includes some small taskbar applets for common things, such as APM, network, CPU, mail status and a clock. There are two graphical configuration tools: IcePref (very user-friendly, but requires Python, PyGTK and doesn't always cover all the latest options) and IceWMConf (Tcl/TK, spartan, but attempts to self-configure itself to your version of IceWM).
IceWM prefers the Window Maker style of workspaces to virtual desktops, but these can be accessed in a number of configurable ways. The versatile taskbar (in non-Gnome versions) can include toolbar, workspace switchers, application icons, programs menu, window list menu and various applets.
This window manager is under active development and author Marko Macek uploads frequent new development releases. A stable release is also available for download, but may lack some of the latest options.
Here are some links to IceWM websites:
Here are some IceWM screenshots, there are many more available from the above sites.