While my internet was down I experimented with creature temperature tags and succeeded in making a creature completely and utterly immune to fire damage.
I decided to test it on one of my forts to make sure it works in dwarf mode as well. I do not backup saves and even though this would be a reasonable excuse to it didn't cross my mind.
I annoyed a group of fire imps until they attacked catching one of my recruits on fire. I deactivated him and he walked back to the barracks (to sleep) burning the whole way, never taking damage. The barracks filled up with smoke but soon I was noticing the occasional extra smoke trail coming from the barracks. Sure enough, the one flaming guy caught everybody else in the sleeping barracks on fire.
I was still not too worried however, I hadn't changed the raws back so my guinea pig would not die, so I figured that I'll just wait til everybody else's clothes burn off too.
Eventually they got hot, very hot. So hot that everything anywhere near any of the flaming residents spontaneously combusted. The wilderness went up in a giant fireball, the water in the well flash boiled dry every 2 seconds, all the stockpiles were on fire, I had molten metal and stone all over my fortress, but most distressing, was that the food stockpile was burning. All the tallow was boiling over, every piece of meat was burning merrily.
The fortress ended in starvation and flaming fistfights. Shamefully, I was too stunned to record the disaster.
EDIT: The experiment however was a HUGE SUCCESS.
[ January 23, 2008: Message edited by: Greiger ]