dungeon construction: gimmicks

The use of gimmicks in a dungeon is a matter of taste. Not everyone needs distractions from the core activities of exploration; however there are opportunities to bring a distinctive feel (yes, you may refer to this as set dressing with impunity) yet the best things is to see stuff being brought along and used because it's just so damned useful. Let's riff on the TV Tropes site who posit an entire console RPG experience with essential criteria and see what's there...

Derelict ghost ship - Take gothic. Add pirate. Tap into the whole Pirates of the Caribbean or Monkey Island vibe that people still smile fondly about.

• Black pearl - it summons a pirate skeleton to fight by your side.
• Flask of rum - This unique brew may provide minor healing, may fortify your combat abilities or even allow you to breathe fire. It will probably get you drunk as well but that's perfectly reasonable.
  
• Ornate cutlass - Probably not magical but makes certain swashbuckling moves easier.
  
• Maps - Some may even lead you to treasure.
• Spooky spyglass - As a regular spyglass but sometimes shows you a ghostly world filled with undead pirates. Or even just X-ray vision.
  

Glowing crystal maze - Probably because console & computer-based RPGs can do glowy and transparent really well. So, going with the flow here... it's glowing crystal versions of equipment and stuff the characters will take with them just in case they end up in a dark place.

• Egg-shaped crystal that can be hurled like a bomb to do your foes harm.
• Enchanted glowing crystal that stores information inside it. Retrieving this information can range from touching it to your forehead to placing it in a crystal stump and watching the pretty pictures that appear.
  
• Glowing crystal sword (or other edged or pointy weapon) with incredible sharpness that does horrific damage to an opponent with a cumulative chance of breaking over time.
  
• Small crystal that glows when you tap it with a tuning fork or sing a specific note.
• Star-shaped crystal that emulates a shuriken except it glows.
  

Ice dungeon - Everyone has this because the whole barbarians in furs thing needs to be done at least once (unless you're in a desert-based campaign obviously) and you can be as grim as Pathfinder, exotic as Sinbad or as downright odd as Kull the Conqueror according to taste.

• Bone weapons - because mining and smithing here is too hard. Do you think keeping a fire going at this temperature is easy? I mean, it's not like there's fire magic around here, is there? Although if you're a fan of the Winter of the World series, you may have your own view. And at least one of these will be a harpoon. Still when you're toe-to-toe with a rust monster, you're the one that's laughing.
  
• Furs (which protect against the cold automatically!) of strange and exotic beasts - some of which you will meet on your adventure. Don't say we didn't warn you, being here means you might even have to skin them as well.
• Unguents and oils which will allow you to survive intense cold wearing less because at some point your furs will be damaged or rendered soaking wet and our art departments must honour the traditions of Frazetta and Vallejo.
  
• Weapons made of hardened ice which do cold damage and as the crystal weapons in the above example are not made to last. In fact, if you head to warmer climes, that enchanted ice battle axe may become an enchanted ice-water mixer.
  

Magic floating castle - You already invoked Chekov by having the castle floating in the air; at some point someone is going to fall off it (villain invoking a mysterious death) or due to dumb happenstance (say someone wants to rodeo a flying monster) on your players' part.

• Climber's harness that lets you attach ropes to it.
  
• Crossbow which fires a grappling hook further than you could throw one. Just in case.
• Winged harness with wings made of wax and feathers which allows you to fly (but needs both your arms to do so) but if you get hit by a fire-based attack it's going very wrong, very quickly.
  

Technological dungeon - Technological need not be modern or sci-fi. Imagine a dungeon based around the designs of Leonardo da Vinci would look... and you get to reference even more advanced technology if you are so inclined. Steampunk might be a bit horrific though.

• Black powder pistol or rifle - The damage need not be huge and the rate of fire is usually much slower than conventional medieval weapons however, the ability to point and go boom has a peculiar allure.
• Sword-breaker dagger - A dagger to confound your opponent which can help in the disarming of said enemy if they've got a sword obviously. In fact any kind of sword with secret flanges or catches adds to the cool factor.
  

What kinds of things would you put in a dungeon?

And what would you bring along afterwards?