Corsair's HXi PSUs have fully modular cables and 80 Plus Platinum efficiency, and they now go up to 1200W. The new HX1200i debuted at the Consumer Electronics Show this week.
Eight 6+2-pin PCIe connectors can be strung from this beastly unit, opening the door to quad CrossFire and SLI configurations with ultra-high-end cards. There are enough SATA ports to power a mini datacenter, plus four-pin Molex plugs galore. The HX1200i can push up to 100A on its 12V rail and 30A each on its 3.3V and 5V lines. Those last two are only good for 150W combined, though.
The USB jack at the back is for communication with Corsair Link software, which lets users monitor voltages, temperatures, and efficiency in real time. Fan controls are present, as well, and it's possible to turn off the 140-mm spinner completely. Based on the the default noise profile in the manual (PDF), it looks like the HX1200i is comfortable operating in stealth mode with loads up to ~475W. Pretty impressive.
Here's a completely gratuitous shot of the guts: