It would be great to be able to select multiple tags to show only notes that have each of those tags. This could be done by, for example, holding Ctrl while clicking a tag, to select multiple tags.
Hypothetical example: I love soup, and have many notes where I review tasty soups, write about famous soup makers, and my own ideas for new soups. I have so many notes about soup, it’s difficult to find a particular one by simply filtering for the “soup” tag. I’m looking for a note I wrote a while ago about this great soup recipe. So I Ctrl+Click “soup” and then “recipes” to further narrow down my search.