Inspired by the table (I rolled a 5) I suddenly realized that on way to make the old chestnut, the spear trap, interesting would be to have a room with a spear trap, sprung. The wall of the room opposite from where the characters enter you have a door. This door is rigged with some kind of alarm. When the alarm goes off, the snake people in a room close by arrive to the party.
Now, imagine a fight in a room with spears sticking out of walls, floor and/or ceiling. Let's also suppose that the opponents are more than one, quick and dextrous. They can probably dodge these spears quite easily, or maybe slither around them. Maybe they even trip and push the player characters towards the sharp spikes.
That would be a far more interesting use of the old spear trap, and a way to make a bunch of weaker monsters more fun to fight.
How about that?