Apple Thunderbolt Display, 2560x1440 27" [$999 USD]
Apple Thunderbolt Display is a 27-inch LED-backlit display with built-in, high-speed Thunderbolt I/O.
Dell 43 Ultra HD 4K Multi-Client Monitor P4317Q
While not available quite yet, this monitor has a 43" 4K display which can be broken down into four 1080p screens at once. With lots of ports, this can replace a productivity