I'd have to say the coolist looking pistol I've seen is my dad's lightweight commander. there's something cool about a pistol where alll of the bluing and anodizing has worn off the front half of the frame and slide.
coolest rifle would have to be my dad's m-14. it's got a really cool Leaf pattern camo paint job, that's also kinda worn off.
coolest shotgun would have to be my mossberg, because it fits.