Un-nerfing thermals, with a twist.

[Iatots]

-stuff-

To make this a little less complicated, you could just have it such that vampires, corpses or someone who has been exposed to very cold temperature would not be visable as a heat signature as they are too cold to see.

That...makes a lot more sense.[/quote]

I think I missed the other discussion thread, but had that really not been brought up?
Just in case, I am gonna dump some more ideas (most 2wild2code):

spacesuits either making you invisible in space because they shield radiation from your body or making you a flare because of the cosmic radiation reflected off space
overloaded wires/hot and cold pipes popping up to make for tryppy tron vision
gunpowder guns making a bright and distinctive flash every time they are fired
cerenkite and erebite popping up, maybe even from inside rocks
lavamoon being intolerable
wendingos popping up in icemoon
shaunting wizards leaving a hot trail
wraiths making cold pools
ovens
solar panels
farts
fires, duh
iceblocks, but not what's inside it, just a big blue squre