What follows is one of my odder ideas and may not be suitable for those who take their dungeons too seriously.
The Devious "Save vs. Conga" Trap
The Set-up: The party chances upon a pair of double doors that lead to a 20’ wide, T-shaped corridor. The branch before them extends 40’ past the double doors before branching left and right and continuing out of sight. The only decoration present in this otherwise plain hallway is terrazzo floor. The party enters the hallway at the end marked "A" on the map above.
The Trap: Once one or more PCs venture out of the shaded area on the map, everyone in this corridor must save vs. spells or succumb to the Conga Curse. Those cursed are compelled to form a conga line and dance down the corridor. The PC farthest into the corridor who succumbs to the curse forms the head of the line with the other adventurers falling in behind him. It is this PC that will chart the course the conga line takes.
Unless restrained or otherwise incapacitated by unaffected party members (dispel magic and remove curse will both break this compulsion), the conga line proceeds down the corridor at half the normal movement rate of the line’s slowest member. The referee should sketch out the corridor and allow the conga line’s leader to indicate what path the line travels. This decision is the line leader’s; the rest of the line must follow the chosen path without question. The line must move forward and cannot double back, reverse or otherwise deviate from making forward progress. The dancers are free to travel from side-to-side and can move diagonally down the hallway as well.
Once the conga line’s path is determined, the referee consults the map above to determine if the dancers blunder into any of the myriad traps that line the corridor. If they do, the normal chance to trigger traps is applied and those doing so suffer the effects indicated below:
Dart Trap –Struck by a fusillade of 1d6 darts for 1d4 points of damage each. A successful save vs. wands reduces the number of darts striking the victim by half, rounded down.
Fire Trap – A blast of fire inflicts 3d6 points of damage to the victim (save vs. breath attacks for half damage).
Gas Trap – Save vs. poison or suffer 2d8 points of damage. Although the area of the gas’s effect is 15’ square, the victim must pass over the trap’s actual trigger to activate it. Note that this trap will likely effect everyone in the conga line.
Lightning Trap – A bolt of lightning strikes the victim for 3d6 points of damage (save vs. spells for half damage).
Spear Trap – Save vs. wands or struck by 1d4 spears for 1d6 points of damage each.
The referee is encouraged to see if a trap activates as each dancer passes through its square and then inflict damage upon affected individuals before rolling to see if the next dancer triggers the trap. This builds tension as the dancers at the back of the line watch helplessly as others conga through the trap, knowing they themselves must pass through it.
Once the dancers reach either set of doors at the end of the corridor, the conga compulsion ends and they may move normally. Once they leave this corridor, however, the curse is reset. Adventurers passing this way again will need to make a saving throw after entering the corridor or fall under the curse’s sway yet again.
The Payoff: If the adventurers survive the conga curse and reach one of the corridor’s far doors, they are free to explore this strange hallway free of the compulsion to dance. In a secret compartment beneath the floor (marked "B" on the map above) is a cache of treasure. This hidden compartment is locked, but does not bear a trap other than the corridor it lies in. The cache consists of 19,000 gp worth of assorted coins and jewelry.