Here's a dungeon inspired by the maps found in Expedition to Undermountain. I really didn't like that map style at all (especially compared to the original 2e Undermountain boxed set maps which I love), but like a train wreck, I just can't seem to look away...
And here's another take on that same map with different bitmap fills:
The dungeon map above is based on the room layout in this one at WotC:
Here's another level in that 3e Undermountain style, this time featuring caverns. I played around with the commands fractal path, explode, line to path, combine path, path to poly and multipoly to make this.