D&D Puzzles

[Einsteinium]

Anyone have any really great puzzles for a campaign? A couple of my favorites:

A puzzle with prismatic spray: They had to trigger the different elements by color in a non-standard order. It was a cryptic phrase they were given before they took on the challenge.
4 ghosts playing cards. Each one gives the next half the cards plus half a card. They have to figure out how many cards each one has to proceed.

A puzzle trap that requires someone to pull a level through a hole in living rock. The trap then triggers, gluing a buckler onto the arm of the monk who liked to trigger traps and rely on his insane AC to protect him. The buckler ends up costing him his supernatural AC bonus. Ahh, the wonders of sovereign glue.

[Razgon]

the magic door with requires the incantation "Ohwha tagoo se Iam" and make the players say it out loud to get it right ? ;-)

the incredibly complex puzzle room, with tiles everywhere that hums softly and makes some sort of picture, and the walls have rows of lit and unlit torches on them, and so on and on and on... The door they are trying to open though, IS open, the handle just turns the other way

[Doopri]

oh my god best punky brewster episode EVER!

*runs and hides in a corner for knowing, remembering and loving that quote*

[DamageInc]

Make them win a game of Othello or Chess in order to proceed. The DM plays the other side.

Have them solve a Rubix Cube in a certain time frame.

Have them solve an Advanced Soduko puzzle in a certain time frame. If someone has a DS for this that would be cool.

[Razgon]

oh my god best punky brewster episode EVER!

*runs and hides in a corner for knowing, remembering and loving that quote*

waaaht? was this referencing to something I said? I dont know Punky Brewster....

[Einsteinium]

There are 3 men that will give you an answer to which path you should take. One always tells the truth, one always lies, and one will kick you in the balls (no save, touch ac attack, always hits) if you ask stupid questions.

Actually, I've thought of making puzzles that are based on knowledge of other video games and geeky things. But I'm not sure if that would ruin the suspension of disbelief.

[raydude]

Penny Arcade talked about a light and mirrors puzzle using actual lights and mirrors as props:

http://www.penny-arcade.com/2009/9/30/

[YellowKing]

I used to just go find "brainteaser" type puzzles online or in books and adapt those to the setting. For instance, a mundane matchstick puzzle could be referenced in game as using human bones.