This first one is called a Cemetery Gun, according to this article from Slate they were used to stop grave robbers. A trip wire connected to the gun would maim or kill the would be robbers and possibly provide the undertaker with another customer, that is what you call a "win-win"
A couple more examples
This next one is a special edition Colt commissioned by the distributor TALO, it celebrates the Dia De Los Muertos (Day of the Dead)
Black Rain Ordnance BRO-PG13 308 Rifle
The folks at Gear Fire Studios created this one-off stock for a 10/22 take-down....
Supposedly one of the 1911s that used to belong to El Chapo
JWH Custom 10/22 bolt
Some AK stocks