I've wanted something along these lines for a long time as well. I have trouble drawing hard lines and distinctions (this is pervasive; things like having a "favorite" anything, or the desire to debate what genres a song or movie fall into, are rather alien to me). This makes picking "one" place for something difficult. Because these are fine/fuzzy distinctions for me, it's also tricky to reason my way back to where I would have put something.
The biggest directory in my document hierarchy is "flotsam".
I think part of the problem is that organizational tactics/schema/heuristics aren't global. We need an array of safe, high-quality tools with good system support/interfaces, and the knowledge to reason about how and when to use which. Patterns.
A stack is probably a fine way to think about organizing mail or clothes. It's probably less useful for deciding where furniture or paintings should go. A filesystem that made sense for organizing source code is probably not the best tool for organizing a movie collection or a lifetime of personal documents. Genre apparently seems like a great way to organize most of the world's movie, book, and music store/sections, but I (unless I can get someone to check the store's inventory system) never know whether what I'm looking for is out of stock or just hiding in the taxonomical hinterlands.
Search can help. Tags can help. Hierarchy can help. Metadata can help.