When I made a 'learning' dungeon for two of my players, I had a room with minions, and then a passageways with spear gauntlets (4Ed). Now I was expecting them to get through it with trial and error, and in doing so they came up with creative ways to bypass the traps. It was a Paladin and Warlock, the same ones playing my campaign now. They were running after an escaping Kobold, and when they got to the passageway they find it's dead bloody corpse. I want to mention that just before they entered, the Paladin unknowingly played with a bunch of levers he found and activated the trap after the Kobold ran away, killing it.
Now they knew there were traps. They failed perception, and didn't have any kind of Thievery skills. So what do they do? Just for the hell of it the room they were in previously was the mess hall of sorts. So the Paladin grabbed a table, and slid it across the floor of the passageway until the spears shot up and destroyed it. Then he just acrobatics checked over it. They would mark where they thought the traps were, and eventually they kept a few bodies of kobolds to heap on a square to see if a trap would activate.
They manage to make it through the whole corridor this way, and even when I threw at them a slinger or two at the end, they just grabbed a table and it provided some cover. I thought this was creative and I didn't even think of them using the tables at all. I just threw them in to give the room more personality.
So! I want to hear other experiences with traps or hazards, in any system. I want to know of creative ways players (or you) got through them in ways the GM didn't even see or think of.