Some folks on my woodworking e-mail list mentioned wanigans. These are apparently a portable kitchen-box (tucker box?) that you bring in your canoe on canoe-camping trips.
This photo (from this website) shows a layout that would make a really good toolbox, given my working habits.
A lot of woodworking toolchests are accessed from the top -- whereas I tend to have mine up on a table or workbench.
Hmm... I originally wasn't considering making a toolchest, as it seemed like I'd get a sore back from constantly bending over to fetch tools. But this approach might be worth exploring.