donjon
There’s a long history of random dungeon generation for roleplaying games, going right back to the first issue of the proto-Dragon Strategic Review magazine, meaning that official generators predate the first Dungeon Master’s Guide. So it’s no surprise that enterprising players have put together their own generators.
The donjon.bin.sh site is no exception. It has a wide variety of generators (some tailored to different rulesets). Most of which make slightly more sense than some of Gygax’s original generators, which could be a bit logic-less.
There’s some planet generators, demographics generators, calendar generators, and name generators, but the basic focus is on providing a set of tools to run a roleplaying adventure.
There’s some influence from other places, too: the cavern generation is inspired by a RogueBasin article. Which means that the influence has gone full circle: You can play D&D on a map generated by an algorithm designed for the roguelike genre which was originally created with the idea that you could generate a dungeon to play a solo D&D adventure.
It’s also nice that it takes the generation a step further and populates the dungeons with details and monsters, formatted in the classically laconic annotation style. It doesn’t go so far as to generate a plot (unless you count the adventure generator) but I like seeing multilayered generators nested inside each other.