There are two areas besides biblical studies where I have always thought the Logos engine would shine.
First, secular literature would be very similar to biblical studies, in that one would have primary sources and the secondary literature in commentary/journals etc... Noet seems to be moving in that direction.
Second, the legal system. Unless there is already some premier software for lawyers (I'm not a lawyer, so I have no idea), Logos would be great for that market. Modules could be set up by state laws, federal laws, case law on the city/state/federal levels, etc... Legal dictionaries could be linked to all resources so that hovering over terms would give their legal definition, and all laws/cases would be linked together so that one could easily find related cases. Legal cases are constantly referencing other legal cases.
Just a thought. Getting people who are interested in literature to fund a software company is like getting people who are interested in guitars to fund the recording industry. [:P] We need people (or at least lawyers) who make money to fund this company!!
All joking aside, I do think Logos would be revolutionary for legal work.