Daily notes. I have a template that prompts me to fill out a number details I might otherwise forget.

A wiki of people that helps me remember details about people I meet or have worked with. Makes it much easier to keep in touch and to remember important dates in their lives.

Sortable todo lists, with due date and urgency information. I can add to the lists directly from any other note using a Dataview formula with the Tasks extension.

Career plans. Project plans. Gardening plans. Recipes (there’s an awesome extension that imports recipes from the web).

Any random writing I might want to do, from short stories to rough drafts of letters to stream of consciousness mind spew that I want to review later.

I use the Auto Note Mover and Dataview extensions, along with backlinks and tags, to keep all of my notes organized automatically. I use the Linter extension to make sure things are formatted nicely. When I started using Obsidian, I used the Importer extension to easily pull in all of my existing notes and lists from Evernote and Google Keep.

Honestly, that barely scratches the surface.