FWIW, those of us with digital cameras absolutely need a UV filter - but it's already built into the camera body.

For film, you definitely need one wherever there's UV (e.g. outdoors). Otherwise, you'll lose detail, particularly in a distant background. I'm with Rowell in that it's OK for things in the distance to be a bit hazy (atmospheric perspective) but UV doesn't look exactly the same. Better to do it with DoF.

I also sometimes find use for a CPOL to kill reflections. One will cause the detail (and colors, but that's a potential fix-in-post) of wet vegetation to 'pop'). But beware the CPOL if the sky is in your shot. Getting it wrong can give you a blob in the middle of the sky that's a major PITA to fix.

Agreed on NDs, but really, really neutral ones are quite expensive. If you're not sure about yours, take a test shot with a grey card each time you're shooting in different light, use that card to set 'neutral' across your subsequent shots.

Also, there are light-pollution filters for night-sky shots (filter out the wavelengths of the two most common streetlights, mercury vapor and sodium) but as LEDs catch on, that's another filter I won't bother with.