I think one of my favorite things about GMing is how damned clever players can be.
Last night, the party was searching a magic/necromancy lab within the depths of the Stone-Scream Clan's keep when they discovered a wand of fire trap with a few charges left in it. Moments later, they were attacked by an Iron Cobra that had been stalking them for some time. The party found it very difficult to damage due to it's DR of 5/-. The rogue was nearly down and things looked kind of grim.
....then, the wizard's player cast fire trap on one of the party's empty treasure sacks. The monk grabbed the sack and, daring an attack of opportunity, grappled and wrestled the Iron Cobra into the sack, cinching it shut. The party scattered, and when the Iron Cobra tore the sack open...BOOM. Fire trap detonated, blasting the Iron Cobra to smithereens. I cannot tell you how pleased I was with their solution to the problem.
For the record, the wand was placed as the result of a random roll, and actually the fight with the Iron Cobra could have taken place in one of several rooms, depending on if the PCs got a lucky Perception check or had stopped to rest somewhere where the construct could have sneaked in. I had absolutely no idea that they would use the wand in that fashion, which is frickin' fantastic as far as I'm concerned.
...of course, karma balanced things out when the party was nearly vanquished by a small-sized mimic the next level down... but that's another story.