I wouldn't want a chain saw, but it would be nice to be able to pick up random objects like say a brick and throw it. Would be cool to be able to run from behind a wall and brick a stalker in the face if you have run out of ammo.
I say a hammer and sickle.
Hook 'em with the sickle, pull 'em in and bash 'em upside the head with the hammer, heh.
Joking, of course.
What I would like to see, though, is more functionality for the knife, like, if you get a drop from a mutant, there's an animation for digging the Flesh's eye out and cutting the optic nerve, or sawing off a Snork's foot...