The Dungeon Dozen provides many awesome d12 lists that are system neutral. I think this one is stand-out as something that an enterprising Old School Hack DM could take and prep; a moon has crashed into the planet, and now it is an adventuring environment. Bizarre, clever, alien, good time. Take a look!
Here is a really clever idea for starting off a game of Old School Hack. The players could basically put a lot of hooks into the background as a collaborative exercise, and you could do this before hand or at the table.
You know what would be awesome? A dungeon with two warring factions.
On the one side, Clan MacDonalds, led by Ronald (who looks like David Bowie in clown shoes tarted up in a yellow jumpsuit with red hair and a clown nose) and his henchmen, Hamburglar and Mayor McCheeze, with their monster enforcer Grimace, their hoards of Fry Guys, their scout Birdie, etc.
On the other side, Sesame Street. The leader, a hardened fighter named Gordon, commanding a mastadon Snuff, a giant kicking emu suffering from retardation (the Big Bird) and a bunch of furry goblins; Oscar, Elmo, Grover, Chloe, etc. The hit man duo, Bert and Ernie. Beware the lurking menace of that mathematically calculating killer, the Count, who may well be playing both sides.
It might scar their characters AND their childhoods, but that would be one hell of a knock-down drag-out dungeon crawl. And some twisted players might just enjoy tickling Elmo. With a very heavy weapon.
fictive --- I actually ran a campaign like that, albeit with a less funny premise. It started out as a one-shot and then became a pick-up game. It was basically a fantasy version of Necromunda using 3.5 rules. Imagine a cross between 'The Prisoner' and the HBO series 'Oz' with a smidgen of 'Gangs of New York'. The characters woke up in an island fortress and became aligned with existing factions --- there were three major gangs, each with different resources. Some started on different sides, and one defected. Weird crap was occasionally hidden in the ruins, new resources would be revealed for the groups to control, shifting walls changed certain areas after a period of time, etc. People would die and be replaced by new arrivals. Two of the characters kind of removed themselves from the action and started running a bookie joint; they later became recurring NPCs in the island's only neutral ground.
"Please welcome to the dungeon these sneaky, furry, porkypigginit, face-stabbing, dick-punching hooligans. They don't play well with the other kids (and tend to eat them), smell like wet yak and their ubiquitous dandruff harbors some fierce alergens, but they cook a mean gumbo, never shirk patrol duty and their A1-class jokes do wonders for monster morale."
And, later, "In key areas like pants-or-no-pants (no self-respecting bugbear submits to the tyranny of pants!), armor and weapons, size/bulk and attidude they are spot-on."
So the 2011 "Secret Santicore" project is incredible. I used an adventure from it for an Old School Hack game, and it has lots of random generators and off-the-wall inspirations. A little bit of everything, and a lot of things you'd never expect.