|I always liked this thing.|
2) The party encounters a third-eye tribe, isolationist firebenders who are trying to master a very dangerous skill. Firebenders are expected to undertake the joining ritual (which involves another third-eye bender burning the emblem into their forehead) while non-firebenders are secretly killed to better protect the tribe and continue making outsiders fear the area they dwell within.
3) A samurai master is offended by the 'skill' of the benders and claims that a master of the elements is a lesser to a master of true human potential. He will challenge any of the PCs to combat, during which he acts like a coach and rival. He supremely believes in his ideals and will be satisfied if he is beaten by non-bending techniques (as it shows they possess the human arts). If he is bent at (aside from perhaps a rock/earth/ice weapon), he will send his personal army after the PCs for making a fool of him.
4) The party is invited to take part in a fishing contest. The contest is usually very spiritual and meant to show their thanks for the plentiful schools of fish brought about by the Great Tigerswordfish Spirit. But a group of conniving types are thinking they can have true fame if they catch this spirit on a hook. Winner gets an ugly hat (looks like a fish) and all they can eat (in fish), plus a small purse of Water Tribe Money.
5) There's a small fortress that's haunted by dangerous creatures and said to possess a vast fortune. Villagers leave offerings at the Foo Dog statues outside the fortress, but none dare enter. A master earthbender lived in the fortress, stationed during a war. His wife gave birth to his only son and he awaited his chance to go home. His ghost animates the statutes in a very clunky earthbending motion, but as they are incapable of speech no one has been able to discern what their purpose is. The offerings keep the spirit active. The elderly headman of the nearby village is this man's son, and he is terrified of going to the old fort. The treasures are some old weapons and swords of superior make, but unless the son is brought to the fort, these items are horribly cursed.
6) The party finds a pacifist temple in one of the mountains, but the denizens within are terrified of bending. To pass through their lands arms must be bound, legs must be chained, and occasionally mouths must be gagged. The monks are harmless and kind, they will feed the party. But a bandit group has set up shop nearby, specifically to kill benders and take their stuff while they're at a disadvantage.
7) A young waterbender drowned in a lake. His spirit has been down to drag people under the water. A mansion has been built by the lakefront and now the spirit is haunting the building like the Grudge-ghost. After the nobleman's daughter begins talking about her imaginary friend, he gets worried (madness runs in the family) and he hires the party to exterminate the "demons" in his house because "all benders are spiritual".
8) Sumo wrestling bending. Earth benders have to stand on small pillars. Water benders on hot coals. Fire benders have buckets of water thrown at them. Air benders wear weights. Any who participate have a chance to make some money---but the dress is ugly, they'll get fat, and someone is rigging the games.
9) A geisha who serviced a water tribe soldier has become the item of public ridicule after a scornful non-bending artist made a political woodcarving depicting her having sex with a squid-shark. She is shamed, the artist feels bad, and now the water-tribesman is coming back with his thugs and he's going to put an end to this (either by killing the geisha because she caused him dishonor by proxy or by killing the artist).
10) The party become the object of obsession for a hikkikomori-type girl. She stays in her parent's castle, never leaves it, but she sends people after the party--often to hound them with questions. She has commissioned an artist to chronicle them whenever he finds them, but he's prone to making things a little too shonen. The girl will get angry if people don't end up with who she wanted them too, and she will occasionally have her parents hire sordid types to influence the plot to be akin to her desired relationships. These thugs will tell the party about this if attacked with lethal force, and they'll try to strike up a deal where they fake a good story. If the party fakes a story the girl will say it sounds non-canon and terrible. She'll then find someone else to fawn over. The party can find a villain for her to fawn over if they want to make a villain very miserable.
11) The party is asked to deliver a large clay barrel of wine to a nobleman on the other side of town. The courier pays well. In the barrel is the dead son of that "nobleman", and now the party is responsible for a yakuza war between two rival families.
12) The party encounter a Guru who is preaching a false path to enlightenment, namely by convincing others to fully embrace hedonism. While this debauchery is fun at first it quickly becomes clear that the Guru doesn't care how far it goes. All it takes is for a few sordid types to say "wouldn't killing be a rush" before he says "Would it? Let's find out!" The Guru means well, he's just horribly misguided. If he survives the encounter, he eventually writes the setting's Kama Sutra (featuring graphic diagrams featuring some of the player characters with features out of place. Like large noses, tiny hands, no feet. Et cetera). This will cause some mockery if the players ever encounter someone who owns a copy.
13) The party encounters a practitioner of Gu, a forbidden sorcery that is used offensively. It involves a lot of smoke and sleight-of-hand, appearing like a new form of bending. The sorcerer is just a master poisoner who enjoys the fear people have when they think he is magic. (Gu shit is fascinating, wikipedia it.). The sorcerer will try to get the party to like and fear him, as he can't do anything beyond poisoning and he fears benders.
14) A large city-state begins preaching about a Celestial Bureaucracy to make people fall in line to the bloated and corrupt bureaucracy that runs the city-state. A few spirits rather like the idea and begin tormenting bureaucrats for tiny slights. The common man is terrified of what this means and some are plotting a revolution against "pompous nobles backed by a divine right that seems to hate them."
15) A group of Firebender freedom fighters called the Torchmen. They liberate slaves and lead them out of the dark and back into the light. But when a Torchman goes bad and starts paying off slavers so they can get away with their trade, the whole organization falls to paranoia. The party is asked to assist in a slave heist to find the traitor and then to kill him while they free slaves. The traitor will try to bribe
16) A formerly nice young man has suffered under spiritual corruption, turning his form large and monstrous. He lives outside town in the wilderness consumed by sorrow. His little sister, a battleaxe of a girl who knows only cruelty, comes to him every so often and tells him what the townspeople think of him. How all the people he loved think he is a demon. She wants him to go on a killing rampage so her not boyfriend (a samurai, but an innocent one) can slay the beast and be made the hero of town. Convincing the tormented being that his sister is lying and manipulating him is about as hard as exposing the sister to the town as someone who is plotting a coup. Most of the townsfolk just think the young man went off to find adventure and never returned, they miss him but mostly they don't think of him that often.
17) The party is targeted by a baku. Every night when they go to sleep they are transported into the Spirit World where they are being pursued by something. When they "awaken" they are tired and grumpy. The baku is a fat trickster spirit who has found the dreams of the scared and desperate to be a spicy treat. If the party is able to see that the pursuer is nothing more than an illusion, they spoil the fun. It will leave them alone if attacked.
18) The party is asked to attend a Noh Theatre production, though the play is too esoteric for all but the smartest of them to understand. However a noble attending sees it as an insult to him and demands everyone in attendance be under arrest for "standing by while I am mocked." The Noh production is actually about badger-moles, but don't try telling that to the nobleman.
19) The party encounters a shirasu rider who is hunting a bounty. His mount was killed and he asks the party to assist in bringing him back to a far away town. The rider is actually the bounty. He killed his hunter and the mount, but not before being poisoned. He's slowly losing his ability to move. He has friends in the new town.
20) The party is hired on for a voyage from one continent to another, but the crew is shifty and very spiritual. The captain is an Ahab type. He hates the spirits and the Earth/Fire Nations. He was once hired to ferry a boatload of new currency across the ocean, but his crew mutined and his brother, a shaman, died. At night on the boat, you can hear bells lightly playing in the distance. It is always foggy.
An Umibozu will prevent the ship from reaching harbor. the spirit of his brother has been twisted into something ugly and terrible. His brother was part of the mutiny, greed had clouded his mind and he acted with hate in his heart. He is condemned and wishes for the captain to follow him into the depths, as the captain is also consumed by hate (for everyone but his brother).
The crew knows rumors about this, but they fear the captain hearing them. The cook was on the ship with the Captain back then, and she remained loyal. She knows the truth but she can't tell the captain without breaking his heart. Hate is all that keeps him going.
21) The party is asked to transport a mysterious stone box through a large cavern. The nobles who sponsored the endeavor fear the contents and won't risk their best men on it. As they help the earthbenders (who are attacked by wolf-bats and baboon-wolves from the nearby hill on a nightly basis), the other couriers begin to have doubts an fears about what's being moved. They think it must be evil, something that they're being used as expendables to deal with. Some fear they're hired sacrifices to some evil mountain kami. One of them is hearing laughter whenever he's underground and he is trying to write it off as the jitters.
The party can help people keep it closed, open it, or just try to move the damn thing. The final resting place is on the edge of a great swamp. The vines will grab at the box and drag it deep into the mud. If the box is opened, a monkey demon appears. It is a terrible spirit, akin to Coyote or another Trickster Deity. It will need to be sealed in stone again to be harmless,. Rubies fascinate it.
The spirit will haunt and cause misfortune and dreadful luck until it finds someone new to torment, like a king or a general. Someone who really cannot handle the spirit.