I had meant to do this for the August RPG Blog Carnival but missed it due to real-life problems.  However the idea stuck in my head so now it's here, hope you enjoy.

Image (cc) miszla

This generator uses the 5 Room Dungeon model, which I always think works better as themes/areas than explicit rooms so the results are designed as hooks and inspiration so it fits better into your campaign.  As always, roll a set of polyhedral dice or use the JavaScript roller at the bottom of the post...

The d20 - The entrance:

1. is up (or down) a sheer cliff.
2. has become the lair of a beast.
3. is hidden by thorny undergrowth.
4. has soldiers camped outside.
5. has sunk underwater.
6. is guarded by a magical construct.
7. was magically sealed.
8. is guarded by an intelligent undead.
9. has collapsed, is there an alternative?
10. is haunted by vengeful spirits.
11. requires a lost key (or keys) to open.
12. is guarded by the local militia.
13. is not located where the maps say it is.
14. has been infested with giant vermin.
15. can only be accessed using magic.
16. is the home of an elemental or similar.
17. is opened by machinery that is missing a part.
18. is trapped in some way.
19. is known only to a select few.
20. is one of many, the rest are decoys or deathtraps.

The d6 - A group of:

1. bandits
2. refugees
3. outcasts
4. worshippers
5. deserters
6. criminals

The d10t - Challenge the party because they:

1. have set many traps inside.
2. want something from inside the dungeon.
3. want something from outside the dungeon.
4. have created a fiendish puzzle.
5. seek help against the other inhabitants.
6. are protecting the dungeon inhabitants.
7. are frustrating the PC's efforts.
8. race the party for their objective.
9. want to claim the dungeon for another power.
10. died here or are dying, messily or agonisingly.

The d12 - The setback:

1. a fake item or object
2. switchbacks and dead ends
3. lingering illusions
4. a person who is not as they seem
5. something from a character backstory
6. a threat that was previously ignored
7. the actions of a traitor
8. the intervention of a divine force
9. the intervention of an evil force
10. hostages or bystanders
11. something missing or incomplete
12. sudden changes to the layout

The d4 - ...mean(s) that:

1. precious time may be wasted.
2. resources may be used up.
3. the party may get split up.
4. a hard choice must be made.

The d8 - The final encounter:

1. is the reverse of what was expected
2. is hampered by the surrounding environment
3. requires the party to split their focus
4. has been designed as a lure or ambush
5. features traps the enemy has set
6. is against the clock
7. is centred around a device or maguffin
8. can be affected by something elsewhere

The d10u - The revelation:

1. a former ally is revealed as an enemy
2. a former enemy is revealed as an ally
3. the treasure or objective is missing
4. there is a hidden treasure hoard or map
5. in the confusion, something is stolen
6. in the confusion, something is dropped
7. a clue highlights a new plot thread
8. a clue turns a situation on its head
9. a clue sheds light on something half known
10. a clue reveals a hidden connection

Click to roll a 5 room dungeon

As always let me know your thoughts in the comments, and I would love to hear your dungeon ideas!