bumpski - 10:30 am on Apr 30, 2011 (gmt 0)

In this instance, you'd probably noindex those documents in between as they really aren't something you want the visitor landing on from a search as they still have one or two more clicks to go.

Although the simple supplemental test appears to be broken again... I've found that these types of pages, sometimes I call them index pages, seem to end up being supplemental.
So perhaps studying supplemental pages could suggest what pages Google would prefer be "noindexed".
(Or the content improved!)
Currently it appears only the "non-supplemental" pages feature works, this search:
site:www.example.com/*
appears to show your "non-supplemental" pages.

Historically you could do a search "subtracting" all your non-supplemental pages from all your pages in Googles index for a given domain, like this:
-site:www.example.com/* site:www.example.com
But this convenient test appears to be "broken" yet again.

I'd be willing to wager a bet that landing on a category page is a contributor to high bounce rates.

On the other hand, if these "index" or "navigation" pages do have some useful content, leading to the correct topic on a given site, they may increase your visitors "dwell" time which I feel is crucial for pages to rank highly with few or no inbound links.

Again it all comes down to a measure of quality doesn't it!
This is an interesting discussion, Thanks! (The best discussions about Google are are those the lead to some "serious conjecture"!)