VDU isn't a term we see too often. It literally stands for “Visual Display Unit”, a general term for any sort of thing that is used to display graphical information for a computer. This includes a variety of familiar technologies, from old bulky CRTs to the current favorite, LCDs, to many future technologies. This article will cover both improvements on the old and developments on the new.
As wonderful as LCDs were as a replacement for those bulky old CRTs, they aren't the end of the VDU evolutionary line.
So, about those bulky old CRTs. The main problem was, well, their bulk. However, they actually offered very high contrast screens, wide viewing angles and a fast response time, often better than more “advanced” screen technologies such as the LCD. A hybrid screen, called an SED, uses the same cathode ray tubes from which CRTs took their name, except makes them much smaller and easier to deal with, like an LCD. The technology has been plagued with lawsuits, but hopefully it will be making a comeback.
OLEDs have actually been around a long time, first developed back in the 80s, but not really utilized until recently. OLED stands for Organic Light Emitting Diode. Basically, they utilize a series of thin organic films, which a current can be run through to make them produce light.
While they are more expensive to produce, they are also thinner than both LCD or plasma, in addition to being faster to change, more durable, lighter, and less power hungry. These displays can be either opaque or transparent. Many major manufacturers are either planning on mass producing these screens, or already have within the last year, for everything from cell phones to large televisions. They're still generally considered a high end type of screen, as LCDs were once considered, but they should be making their way down to the everyday level within the next few years. This article from Science Daily offers an excellent overview of the technology and its applications, albeit from 2005.
Projection technologies, first popularized for educational and home theater uses, are now starting to be used for your everyday computer. This allows the computer screen to be as big as you want, and it is infinitely portable, capable of being projected anywhere you please. All you need is a blank wall and you're good to go! Projectors can also be connected wirelessly to a computer. In fact, projectors may even be combined with touch screen technologies.