Since no one has mentioned it yet, I'll throw out Return to the Temple of Elemental Evil.
For classics, I'll say Tomb of Horrors. I never actually got to play it, but some old timers I know still twitch and reach for d6s if you so much as mention it.
A more obscure one is Labrynth of Madness. Second edition, it required the PCs locate magical runes that were hidden in the most obscure places in order to get through the thing. The traps bring a whole new meaning to rat-bastardry. An example
SPOILER ALERT
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One trap was on a teleporter. These were done 'teleport circle' style and were common in the labrynth. Now, when your group is going through a teleporter like that, what does the first guy through do?
That's right, he steps forward to let the next guy through. Unfortunately, that section of floor is illusionary. You fall sixty feet. FOrtunately your fall is broken by a dead gelatinous cube, held in place by a narrowing of the tunnel, so you only take half damage.
Unfortunately, the cube's enzymes are still active, so you have to roll saves or become paralyzed. Even more unfortunately, the force of your fall wedges you inside the dead cube, leaving you to sufficate if you fail a save.
Now, when your buddy comes through the TP, he sees his friend gone! No one can yell, becaus ethey are buried in cube goo. And the illusion is still there. So until someone can climb tot he top of the cube the players tumble one after the other into the goo.
Now the cube's body does have hit points. Every character falling does damage, as does digging a character out. When its out of HP, it loses cohesion. Dropping the characters. Another sixty feet. Onto spikes.
God, my players hated that module.