Silver Wolf Desktop is a MacOS-style "desktop environment" package for Windows 3.1. Developed by Silver Wolf Software (http://www.silverwolf.com/).
I used it before Windows 95 came along, and I think it was pretty neat of software. I didn't had time or money to register it, though.
It basically had its own "metadata file" thing, whose likeness I much, much later spotted in Nautilus.
One of the coolest features of SWD was that it supported long filenames and aliases. In other words, you could give a long name to a file without renaming the file at filesystem level. I have often wanted to see this feature in Win9x and Linux file managers - say, these days I could give directory "mp3s" a long name "Music Files", refer to the file from desktop as "Music Files" and as "mp3s" from elsewhere. Closest I can get in either of the new systems I use is a Shortcut or symlink.
In addition it also supported trash can, file finding, histories, all sort of other things.