-The Diary - obvious.
-Nagini - also obvious, plus Fantastic Beasts tells us she has a human form.
-The Locket - talks to Ron and presents visions to him. Easy.
-The Ring - houses the Resurrection Stone, which can bring people back in a similar fashion to the Diary, as 'memory made nearly solid'.
-The Diadem - is supposed to enhance the wisdom of the wearer. Shades of the Archchancellor's Hat here - maybe it just straight-up talks?
-The Cup - the Wiki speculates that it might have magic food-transporting powers, and I'm oddly taken with the idea of it attempting to flirt by just randomly giving Harry purportedly erotic or aphrodisiac foodstuffs - possibly very badly. "Oysters in whipped cream? What am I supposed to do with THAT?"

And if we count Harry as a Horcrux, then... he's Harry Potter.

hS

I say, knowing nothing of the particulars of this case.

It's still very much a category, though.

As for the mechanics... not going there. XD