Wizard with a Gun's reveal trailer. The game I'm currently working on.
The Luminous Arena is a highly scripted area that I made which forces players to change up their gameplay styles in order to overcome challenges.
The the Wastelands of Fallout 3, I set a long line of cars up to be just far enough apart to damage each other enough to eventually explode, but not all at once.
Gold Ribbon Grocers is an abandoned mini-mart with an overly complex physics-based machine. The swinging trap knocks over various boxes, which fall onto a pressure plate, which sets off a pitching machine that knocks a fire extinguisher onto a bear trap. The resulting explosion knocks loose a bunch of hanging grenades, which ignites a gas leak. The resulting explosion makes some loot fall down a hole in the ceiling near where the player started the sequence.
Tarroch's Rift is a dungeon I made by myself, using a slightly unorthodox procedural method that allowed players to continuously descend instead of traversing horizontally.
Tarroch's Tomb is a challenge area that I created and scripted. It's intended to be an end-game challenge area where players can test their strongest builds with continued waves of more and more difficult enemies.