I was hoping not to invest in an iPad (considering the price and way over qualified) just to use as a second monitor on-the-go. I'll look into an Android tablet while using a similar application since you've had luck working off a tablet as a 2nd screen.
Being able to hang a tablet off of your laptop's screen (like the way that kickstarter project mentioned by someone else does) would be nice. By the way, my laptop bag has a convenient pouch for a tablet.