This Observable Framework project allows me to test different things, for example to port “classic” D3 and Plot notebooks to dark mode, or to play with new features and libraries.
I don’t guarantee that something you find today will be here tomorrow (in fact, quite the opposite). So if you see something interesting, use it—but probably don't link to it if you want the link to persist. You can check what license a page has by going to the source mentioned. If there is no source, or the source has no license, reach out to me and I’ll clarify.
The contents is not structured (yet), you have to search.
If you want to contribute something, open a pull-request. If you want something that you don’t find here, open a feature request.