I was quite amazed when I hit a bat in the village or puppy cave and it dropped, of all things, an anvil. I had never seen anything carrying an anvil, let alone a bat. Very funny.
To compete with unusualness, I killed a mugger in Lawenilothehl and he dropped a pair of seven-league boots.
I've also seen seven-league boots in the black market shop, which was funny. I died before I could buy them.
I've seen an amulet of life-saving there as well, and when I went out trying to gather the gold to buy it (even cursed, it was worth the $7800 or so it was going for ), I found another amulet of life-saving as a random drop in the the Keethrax cave.
I guess if you play obsessively for a few months, you'll find all kinds of interesting stuff.