A big +1 to archiving! I'd love to have notebooks used for previous jobs not appear in the web clipper or mobile app interfaces, for example — I'm almost certainly never again going to be adding something new to those collections, and space is at a premium in those interfaces. Furthermore, the web clipper's autosuggest feature is great when it's working-as-magically-intended, but it does have a way of frequently wanting to stick things in "past job" notebooks I haven't touched in months. But, as others have said, I do want to be able to have those notebooks, their notes, and metadata still readily available for searches. Gmail's Archive behaviour would be a good starting point, although I'm sure it's hardly the definitive model.