Marginalia50 began as an exercise in applied cartography — not of land, but of the web. The name references the practice of annotating maps in their margins: the notes surveyors leave beside the main grid to record what resists easy categorisation. We found the metaphor apt. The web too has a core territory of well-mapped commerce and a sprawling margin of harder-to-classify resources, and we set out to chart both. The directory holds 826 destinations arranged across 22 subject territories. Each territory has a name chosen to describe the general character of its contents: Medical Precincts for health providers, Capital Exchanges for financial services, General Survey for everything that defies a single label. The names are working terms, not rigid taxonomies. A destination that straddles two territories is placed where it seems most useful. Every listed site is reviewed before inclusion. We check that the destination is active, that its content broadly matches the stated category, and that it presents itself in a manner consistent with a publicly accessible web resource. We do not verify claims made by individual sites, and inclusion does not imply endorsement of any product, service, or opinion hosted at a listed address. Submissions are welcome and processed as time allows. The form on the Add a Site page accepts a URL and a category selection; a brief description is generated automatically from the submitted domain. Most approved submissions appear in the index within a short processing window. Sites that fail review are not listed, and submitters are not individually notified of rejection. Marginalia50 is maintained as a public reference tool. It has no commercial relationship with any listed destination, accepts no payment for inclusion, and carries no advertising. The index will remain freely browsable for as long as the survey continues.