In the current game guns can only be used to shoot with. I think it would be a nice feature to the game, if guns could be used blunt melee weapons or as bladed melee weapons if a bayonet is attached.
The damage dealt would be comparable with hammers for handguns, baseball bats and farming hoes for rifles w/ and without bayonets, while having a slower attack speed than baseball bats or farming hoes.
This would make guns not completely useless without ammo or for stealthily killing zombies, while still keeping the benefits of real melee weapons.
In order to realize this in the game, i would suggest adding multiple firemodes to all guns (also for the realism, as many select-fire guns are currently fullauto only) .
For example: fullauto, semiauto, melee
or: singleshot, doubleshot, melee
or: semiauto, melee
A gun would automatically switch to melee mode, when there were no bullets in the mag or the gun and switch back to the previous fire mode after reloading.
I know there are other feature requests dealing with fire modes and gun melee on their own, but i thought i'd extend those to a new concept of melee and fire modes in DayZ.