Here's something I found in a Swiss gun magazine a few years back. It's a revolver called the "Pfeifer Zeliska", and it's made by an Austrian gunsmith who is probably all kinds of nuts.
For the ultimate in hand-held stopping power, this puppy is chambered in .600 Nitro Express. That's the genuine elephant cartridge used for Very Large Things That Can Kill You Dead. They mention the chronographed ballistics out of this thing, and I had to do a conversion from joule and meters/sec. to foot-pounds of energy and feet per second.
It launches a 900-grain bullet at 1,515fps, for a muzzle energy of 4,586fpe.
.600NE has roughly twice as much oomph from a rifle barrel, but even the reduced muzzle energy out of that monster wheelgun is still well above anything else offered by anyone else. It's half again as powerful as the .500S&W, and recoil is probably, erm, excessive.
Is there a need for a revolver with that kind of ka-boom? Not really. (There's also no practical purpose for it, unless you figure out that time machine thing and start going on hunting trips to the Jurassic period.) However, I'd buy one for two reasons alone: first, it's a neat piece of engineering, and second, it would make the gun control crowd piss their pants in terror.
Alright, make that three reasons: it makes one heck of a loud BOOM, and making things go BOOM is one of the primal joys in life.