...in the search box (top right corner of e.g. this page) there is a link named "advanced". This goes to a page with boolean operators.

That's an example of what I love about the Mudcat - there's always some new trick you hadn't known about until someone points it out one day.

The clever thing about the BS non BS split was that it's there if you want it, and you can dispense with it if you prefer, and that's a principle that I think should be followed in this kind of thing. If there's some way in which people who would like things categorized can push a button and see it that way, and those who prefer it more random can keep it that way, I think that's the way to do it.

I'd imagine it would be possible to do that for tagged threads without too many complications.

As for tags, the problem, with too specific tags is that it can be hard to see which to use sometimes - I'd sooner just have "Songs", "Tunes", "Events" "Obit" and "Instruments" for the music side of it, along with Folklore (though I'd sooner call that History, so it'd be a natural home for people reminiscing about some coffee bar in the 1960s as well as the ins-and-outs of the Morris tradition in the 17th century). And maybe another for "Issues" to provide a home for the stuff about licence law reform, and what-is-folk. That's two fewer than we have at present.