It would be awesome to be able to place collections and smart collections into nested folders.
For me I use smart collections to organize sounds that I have designed, but I have so many different clips of different kinds at this point its starting to get a little crazy to sort through my collections.
The tagging and automatic organization via smart collections is amazing, but having the ability to nest these smart collections into different folders would reduce the overwhelm for me of scrolling through thirty different smart folders to find something.