What niche subject do you know a lot about?

Compost

Bollards, roads signs and other road signalisation. It is honestly a problem.

what's your favourite type of bollard and why?
- I am a big fan of the Slovenian/Austrian combo snow pole+bollard. I think they are such a clever thing for places where it snows enough to cover the actual bollard and doesn't require workers to drag around a bunch of snow poles every winter, they just gotta pull them out.

Grammar

.

I work in a museum space. Any recommendations for implementing various forms of holography to create interesting exhibits?

Lord of the Rings. Not as much as the insanely awesome folks who memorized the Silmarillion, but I know a lot about The Hobbit and The Lord of the Rings.

Username checks out

The history of food culture in Asturias in northern Spain.

I surfed the north coast of Spain many years ago, and the food was epic. I never forget that trip. Where can I learn more of the Asturian food history?
- I write about it in English at https://eatingasturias.com, assuming self promotion isn't a terrible sin here

Current Canadian politics.

GIS (Short for Geographic Information Systems)

My brother had expressed interest in this, but I don't entirely understand what it means. Would you give me a brief eli5 overview maybe?
- Sure, I'd love to. It's more ELI10 that ELI5 tho...
  It's very likely that you or your brother played an adventure game or an RPG on your computer. When you get lost in such games, or simply want to know where your character that your playing needs to go, you open up a digital map. On that map you usually get all the information you might need - what is your current location, where your active quests are, maybe even different parts of the world, if it's divided into 'zones'.
  Such interactive maps are a great example of what GIS does. The town or city you live in, usually uses a similar interactive map. Instead of active quest, their system might show things like parks, points of interest like turist spots or parking spaces. It might also show how many people live in what part of the city, their average age and income.
  Beside your local municipalty, other companies or organization also use GIS. Their systems might show other (spatial) data that interest them.
  Fire department might have a system that shows historic data - where they've had most fires, what the current situation is and where their units are dispatched at the moment.
  Your Internet provider might have a map of their network and any issues along it. Maybe even overlay of property lines, so that they know who to contact when they'd like to expand their network and put new optical cables in the ground.
  The system that collects and shows similar data as mentioned above is usually referred to as a Geographic information system. In it's most basic definition it is a system for collecting, storing and displaying spatial data.

Sexual kinks

Medieval European building techniques, specifically heavy timber framing and lime plaster

Depends on your definition of "a lot," but I know a fair amount about Star Trek

The TV show Big Brother.

Car painting and repairs, high end wholesale bicycle market from 2009-2017

The appearance and behavior of quite a few types of cancers

Fireworks and pyrotechnic chemistry.

Growing and managing strawberries in a commercial setting.

The history of computing and video games.

I wouldn't say I'm a world class expert or anything, but I know enough to talk your ear off at a dinner party.

Southern Appalachian medicinal herbs

The lottery, suits and the pope.

Obscure game history

Just: Brain jank related to plurality (the situation of multiple people living in the same brain).

Cat: For clarity, much of it was learned through direct practical experience.

Supreme court cases. There are some real doozies, not that anyone irl cares.