Cairo Shell - Cairo is a desktop environment for Windows.
BB4Win - BB4Win (Blackbox for Windows) is an alternative shell for Microsoft Windows.
Talisman Desktop - Talisman Desktop is a configurable Windows shell replacement introduced in 1997 by Lighttek...
bbLean - Alternative Windows shell
bug.n - Provide views (i. e. virtual desktops) for showing only those windows, which you need to do your work..
LiteStep - LiteStep is a replacement desktop interface for Windows.