Alright, with all of the talk of new animal dungeons, I decided to start a thread to collect them all in.
My favourite one I've already mentioned a few times: giant ant nest dungeon. Pretty much just a huge ant mound and the boss would be an hearthling sized ant matriarch. Some stuff you could could find in the dungeon would be ant pupae (food), ant mandibles (curio) and regular ants you would get from smaller nests.