Where is it located?
Here are some things:
maps (state maps, cycling route maps, adventure cycling touring maps)
a really big map on the wall elevations and with your location circled or pinned
a town map with groceries, camping, etc pointed out
cliff bars
lights
all sorts of batteries
saddle bags, handlebar bags.
gps units
bike computers
spare bolts of assorted sizes
zip ties
maybe some specialty items like those portable lock ring removers that don't need a chain whip or wrench
also the fiber fix spokes
Topeak Road Morph