I just played around with the new Lenovo W700ds laptop, complete with two screens and built-in Wacom tablet, and it's a monster. It's not exactly portable, but it's as feature-filled as laptops get.
Of course there's the secondary screen, clocking in at 10.6 inches and popping out of the side of the 17-inch screen. But there's also the built-in Wacom digitizer. And the fingerprint scanner. It is, frankly, awesome. But the cost of said awesomeness is size: this thing is an absolute tank.
Weighing in at about 11 pounds, this is more desktop replacement than portable computer. Sure, you could carry it around with you, but expect back problems if you try to do it too often. Oh, and the battery life? Two hours. Er, yeah. But for people who are looking for a boatload of functionality (not to mention two screens) in a laptop, there are few peers to the W700ds out there.