I agree with Tomass that we need an improved approach to Nesting. I also tend to agree with Jefito that we should keep Notebooks and Tags separate. What Tomass is describing is essentially a Nested Tag solution which I believe EN could benefit immensely from. See my reply on: Feature request: Autotag notes with tag hierarchy of nested tags http://discussion.evernote.com/topic/37385-feature-request-autotag-notes-with-tag-hierarchy-of-nested-tags/