Have a separate section (not Sources) to link individuals to other non-primary sites and pages
I spend a lot of time on MusicBrainz, a massive database for recorded music. Aside from having documentation and style guidelines that puts FS to shame (and volunteer teams dedicated to maintaining and building them), they have something else that we could sorely use: a system for linking their entries (bands, people, albums, songs, etc.) to those same entities on other well-known music database sites (plus Wikipedia, a few social media sites and online stores). On the artist's profile page, it looks like this:
Currently, we only have Sources, which ends up getting a lot of links to things that aren't real sources added to it, like Find a Grave, Wikitree, My Heritage, the ubiquitous and useless "Ancestry Family Trees", etc. Dumping all these links to unverified content on user-generated sites into the same place as actual primary source documents gives the impression that they are equally authoritative, when they're absolutely not.
Ideally, we'd want to link individual profiles here to the pages for that person on other sites that have the same shared, global design, like Find a Grave, Wikitree, Wikipedia (if the person is famous enough), but not to entries on individual private trees, such as Ancestry.
Less reliable secondary sources like the U.S. and International Marriage Records, Family Data Collection, or Millennium File should have a separate panel called something like "other mentions".