Usually only reserved for the Japanese made by companies we've never heard of before, USB graphics adapters provide an alternative to adding another graphics card to your system, to add more graphics outputs from your system.
Now that EVGA has entered the fray and decided to enter this market, they should be easier for other parts of the world to get hold of including Australia and Europe. The two UV Plus models launched are UV-12 and UV-16. Simple attach them to a spare USB port on your system and you'll gain an additional DVI-I output instead of filling up your expansion slots with another graphics card.
The cheaper UV-12 box supports up to 1440x900 at a refresh rate of 60Hz and 32-bit color while the more expensive UV-16 supports up to 1680x1050 at a refresh rate of 60Hz and 32-bit color. It's a shame they don't support higher resolutions for people using 24-inch to 30-inch displays but it should be adequate for most users of 20-inch to 22-inch LCD displays. Keep in mind though, despite the typo, these products have nothing to do with DisplayPort - they use DisplayLink technology.
There are more details over here at the product website.