.700 Nitro Express
The cartridge that restarted an industry - the .700 Nitro Express, or "700 NE", is the worthy successor to the .600 Nitro Express.
700 NE was originally developed in the late 80's by Jim Bell and William Feldstein. Coincidentally, legendary big game rifle makers Holland & Holland of 33, Bruton Street, London, had just ceased production of their 600 NE rifles, and they refused to build one for either Bell or Feldstein. This eventually led to the snubbed buyers successfully enticing H&H with their recently developed cartridge, and demand grew so quickly for the newest model of H&H rifles that there is, as of 2011, still a backlog at H&H for these incredibly expensive rifles. The unprecedented demand has prompted H&H to successfully restart production of the 600 NE and several other lines of rifles at great profit.
The 700 NE superficially resembles a simply scaled-up 600 NE. The 700, however, is a completely new case, not based on a then-existing design, and fires a 1000 grain (~2.3 oz,~65 gm), .700 caliber, solid copper bullet at speeds around 2000 fps at the muzzle, for a muzzle energy around 9000 ft·lbf from H&H's 26.5 inch double rifle barrels.
Other than its incredible physical size (it has a case capacity of 317 gr H2O/20.6 cm³ and an overall length of 4.2 in/10.7 cm), the 700 NE is also known for its incredible cost - factory ammunition goes for about US$100 per round, in 2010 dollars. But then, the H&H rifle you're likely shooting it from goes for a low-end of US$150,000.
The typical 700 NE H&H rifle owner is either a collector who would never dare fire it, or someone who habitually hunts large, dangerous animals and wants something with more precious wood and gold inlay than an A-Square Hannibal chambered in .577 Tyrannosaurus.