I just wrote a maze generation demo in Javascript, which you can see here:

http://static.opengameart.org/procgen/

Relevant javascript files (note: these are by me and are free to use however you like, under the CC0 license):

• http://static.opengameart.org/procgen/procgen.js
• http://static.opengameart.org/procgen/procgen_maze.js

I'm working on dungeon generation too, but it's not really ready for primetime yet.