Furthest Farthing’s Frog Pond – it’s an interesting concept, but it’s more an interesting location with an encounter than a dungeon. Also, if you need trigger warnings, you probably shouldn’t be playing D&D. Still, the idea of a cursed town where everyone is on the verge of suicide and the players have to do something to stop it is neat enough to steal. I did something similar once with Towers of Dream, but that focused more on the Towers than the town. If I ever get around to playtesting Towers, I’ll almost certainly use the driven-to-suicide mechanic.
Lantern of Wyv – Really impressive amount of content and real-estate crammed into this one. Pick out some stat-blocks and some wandering monsters, and you’re good to go.
A Stolen Song – This a really workable B/X dungeon with a cool puzzle; all you have to do is look up the stats for the listed monster. Recommended for mid level parties with magic weapons. Best of the 1st place OPDs, imo.
The Panopticon – An interesting piece of art that is not easy on the eyes, but I can’t imagine actually trying to run this. It’s more of an abstract for a “clear out the 666 layers of the abyss” type campaign than a playable module.
The Heist – The isometric art for this is pretty cute, and it’s hard not to like a one page dungeon whose (obliquely) stated goal is to knock a 1st level party up to level 2 if they survive, all in one page.
Sepulchre of the Abyss – At first glance, there’s not a lot going on here except for being an incredibly easy to pick up and play micro-dungeon. Which is really what you should be looking for in a OPD. But the fact that it’s an underwater dungeon with random flood/terrain effects for each room make this hella evocative of Leiber’s The Sunken Land.
Into the Awaroth Woods – Beautiful art hampered by a rather cramped choice of font, but it’s cramped in the same way that the old scans of Keep on the Borderland are, so nostalgia? Anyway, a lot of great set pieces in this one, which could easily be fleshed out into a full campaign, reminiscent of the expanded “Terror in the Gloaming” scenario.
Escape the Oubliette – This is a cool “death trap” scenario that your players, unless they like that sort of thing, are guaranteed to hate. They start in naked and afraid in a cave deep underground and have to escape from a deep pit before the river floods the well.
Shambling Throne – This is one of those comic OPDs that’s more to be enjoyed as a work of art than seriously attempted to run. I mean, I suppose you could try to run Ravenloft off of those comics that WotC put up a few years back, but isn’t it better to just try to enjoy this sort of thing for what it is?
These and countless more OPDs can be found over at Random Wizard’s OPD site!