I've been collecting random dungeon generators for a while now. The funny thing is that although I love them, I never use 'em. Guess that is because I've been running a published module for so long. Anyhow, although some of these have stats for particular versions of D&D, they really are suitable for whatever version you play. Enjoy.
Donjon's Random Dungeon Generator - Pretty neat in that it provides monster stat blocks, a dungeon map, etc. Tons of options, such as map style, layout, etc. It even generates a wandering monster table. The link there is for the d20 version, but there is a 4e one at that page too.
Myth Weaver's Dungeon Generator - Lots of options here and it populates the dungeon with monsters and treasure as well. Some times it dishes out d20 stats for specific creatures. It provides stats for the traps, too.
Gozzy's Dungeon Map Creator - This one only makes a map (which might be a plus for some). Plus it includes a random room map creator as well.
Paratime Design's Maps - This page doesn't have a generator, but does have tons of free maps for castles, dungeons, buildings, cities, etc. Pretty sweet.
Dyson's Random Morph Map - One of my favorites as the maps created look sort of hand-drawn. It puts together the map based on geomorphs from the A Character for Every Game blog. This guy made a cube out of it.
Risus Monkey's Random Map - This one is very similar to Dyson's (and the site notes it was inspired by it). Again, I like the feel of these maps because they are based on geomorphs and the result looks hand-drawn. Troll and Flame created an interesting Dungeon Geomorph Cube Project based on this site.
Note: I suspect the last two ones served as inspiration for the awesome DungeonMorph Dice Kickstarter project. EDIT: The man behind Inkwell Ideas (see below) is also the creator of the DungeonMorph Dice. He does indeed cite the two sites, and many more, as inspiration.
Dizzy Dragon Games Adventure Generator - This one generates a populated dungeon level and encounters based on d20 Pathfinder, Moldvay/Cook/BX, or Moldvay Basic (although it doesn't create stat blocks). The dressings can come from the 1st edition DMG.
The Wizards of the Coast Random Dungeon Generator - This one is pretty great for d20 (I'm not sure if there is a free 4e one out there from WotC). You can select which monster sources (e.g., just the core books, or add in the other Monster Manuals, Fiend Folio, etc.). It even provides boxed text, if you are into that kind of thing.
Inkwell Ideas - This guy has a ton of generators of various kinds (not to mention excellent mapping software).
- Dungeon Generator
- City Generator
- Village Generator
- Inn Generator
If anyone knows of more map or dungeon generators, please share!