I'm pretty behind on my podcasts (I mostly listen in order), so I've only just listened to the 1/24 episode of The Talk Show. Early in Gruber's conversation with Ben Thompson, they mentioned an app called Duet. Well, really it's a desktop app working in concert with an iOS app. When running on a Mac and an iPad connected with a cable, it allows you to treat the iPad as a target display.
Dual monitor setups have rarely appealed to me because of the nature of my job. I'm only at my desk about 50% of the time, so why get used to the extra monitor if I could only have it some of the time? And once I received my Retina MacBook Pro for work, what external display would live up to the gorgeous screen attached to my laptop?
But I always have my iPad with me (a first generation iPad Air); it travels in my computer bag right beside the laptop. So not only can I use a dual display at my desk, but I can take it home with me, or to any place I might be working for more than an hour. Sure, it's a small screen for a second display, but it's a Retina display like my laptop, so even at small sizes, the text is sharp enough to be readable. I'm already finding it to be incredible useful. The desktop app is free, and the iOS app is an easily worth-it $7.99. Highly recommended - unless you're already hooked on some 24" beast.