Laptop screens are small. Desktop monitors aren't portable. Using the two together is a constant tug o' war between portability and screen size. Not with the Toshiba 14-inch Mobile Monitor though. It's a portable, USB-powered monitor.
Toshiba 14-inch USB Mobile Monitor
Screen: 14-inch LCD with 1366x768 Resolution
Size: 13.4W x 9.4H x 0.6D inches
For: PC and Mac
It does exactly what it's supposed to do - which is to be a monitor that can actually hangout with a laptop. Connected to your lappy through USB, the screen's 1366x768 resolution isn't going to wow your pants off but the added 14 inches makes a huge difference. Do the maths, two screen is always better than one. The piano black monitor comes attached to its own mock-leather carrying case (which doubles as its stand) so it's always protected and classy enough to carry around (weighing less than 1.4kg). And because of the carrying case/stand's wide base, the monitor acts more like a tablet-with-an-awesome-case than a traditional top heavy monitor. Which is to say, you can prop this baby up anywhere - your bed, your couch, your lawn, etc. $US200 is a great deal for something as versatile as this.
The screen, when its plugged into USB, is noticeably dimmer than your laptop's screen, so you'll probably only throw secondary tasks on it. Technically, you can reach maximum brightness by adding a power adaptor but that destroys the whole portability point (and isn't even included with the monitor). Also: If you take away a USB port from me (like this monitor does), you better give one back to me (which this monitor doesn't).