and other random guidance I've found by perusing the "on-topic / off-topic" sections of help pages,
there seems to be a need to help disambiguate sites. While the current sites page is pretty, it doesn't really do a good job of directing would-be users to the appropriate sites for their questions. Likewise, this Map of all SE sites (except the 3 biggest) is interesting, but not really the answer either.
Somewhere, there should be some sort of listing that summarizes the on-topic locus of each site, and it could be as simple as a list of the sites, along with their short descriptions next to them.
Ideally, there would even be a simple little search function that would allow a user to search through all of the site descriptions as well.
Simply put, guidance around the appropriate site seems in order, and it would be nice to capture it in a straightforward fashion.