I've filled up over a dozen Field Notes notebooks over the last year or so. I keep all of them in a Ziploc bag in my desk, with the dates written on the covers for future use. (I also scan them and keep them as PDFs) Admittedly, it's not a great system, but it works.

The guys over at Field Notes have come up with a solution — the Archival Wooden Box. Built from American 5-Ply, Cabinet-Grade Birch, these boxes can hold over 60 notebooks, and come with a dozen dividers to help you keep your notebooks organized. The box is $34.95.