You can make icons semi-transparent in Quick Look, with previews of the folder’s contents in the folder.
defaults write com.apple.finder QLEnableXRayFolders 1
Once run, and the Finder is killed (or a reboot performed), Quick Look ends up looking something like this:
To undo it, simply change the 1 to a 0 from earlier:
defaults write com.apple.finder QLEnableXRayFolders 0
