I know there are a lot of plugins like this for Leopard, but I am wondering if anyone knows of any for snow leopard?
I want to be able to view the contents of a folder when I press space while hovering over it.
Running this script in Terminal.app might do what you want:
defaults write com.apple.finder QLEnableXRayFolders 1
When you activate quick look on a folder, the folder will appear transparent and will cycle through the icons of the folder's contents. Check out http://hints.macworld.com/article.php?story=20090912030240376 for a discussion on and demonstration of this.
From the developer of such a plugin:
Snow Leopard finder stopped to launch QuickLook plug-ins for folders except application bundle and some other special folders. Folder.qlgenerator will not work if this limitation is by design.
I don't know the internals, but you could petition the developer of Total Finder to implement QuickLook support for folders (don't know if it's possible at all, though, and you should be comfortable with software that modifies the memory contents of the software you use to manage your files). Path Finder also does not support it, so it might actually be a more complicated issue.