I've been experimenting with simple spatial search in BioStor, as shown in the demo below. If you go to the map on BioStor you can use the tools on the left to draw a box or a polygon on the map, and BioStor will search it's database for articles that mention localities that occur in that region. If you click on a marker you can see the title of the article, clicking on that title takes you to the article itself.
This is all rather crude (and a little slow), but it provides another way to dive into the content I've been extracting from the BHL. One thing I've been doing is looking at protected areas (often marked on Open Street Map), drawing a simple polygon around that area, then seeing if BioStor knows anything about that area.
For the technically minded, this tool is an extension of the Searching GBIF by drawing on a map demo, and uses the geospatial indexing offered by Cloudant.