I've purchased a USB monitor for use with my laptop. The monitor uses "DisplayLink" technology which, in short, sends both power and video signal (and I believe the option of audio, though this monitor doesn't support it) over a single USB cable.
Thus far I've tested it using USB 3.0 on a windows desktop computer and USB 2.0 on my late 2011 MacBook Pro.
First a little caution: There are two versions of this monitor in the wild. There's the regular MB168B and the MB168B+. The former has a resolution of 1366x768 which seems to be the norm for these USB monitors. The latter, however, has a resolution of 1920x1080 which is "Full HD" for those who are counting. For my money it's very much worth the extra $40 bucks or so to get the 1080p version. Most laptops these days come with displays better than 1366x768 and it would be very disappointing to sit this beautiful monitor by your full hd laptop and have the resolutions be so different.
My fears when purchasing this monitor were two fold.
1. Will it work well with Mac. I'd seen various reviews that said it did or didn't.
2. Will it work well with USB 2.0 as NONE of my laptops currently support USB 3.0 which is what this little guy was designed for.
The answer to both of these is a resounding YES. The only quirk I see with Mac is well documented. You can't change the brightness from a Mac. I haven't found the need to because it looks great as it is. They say, however that you can plug into a windows machine, change it and it'll stick when you go back to mac. I'll edit once I find time to test this.
The other things I wanted to test was how it interacts with VMware:
It works very well with a virtual machine running full screen on the other monitor. This should only be possible (on a Mac) with Mavericks and greater with the new feature that allows for full screen on multiple monitors.
I also attempted to use it for multiple monitors for the virtual machine (i.e. inside the virtual machine connect the display and try to setup multiple monitors inside the virtual machine). This didn't work but might still be possible by using dual monitors on the host machine and setting up VMware to have the guest machine use both monitors. I've done this on a windows host with multiple monitors, but I haven't yet found a way in VMware Fusion for Mac. Again, I'll edit when I have used it for a while longer and I'll try with virtual box and play around with settings.
Overall I'm VERY impressed with the monitor and it works perfectly well with USB 2.0 so if that's all you have like me then I wouldn't hesitate.
Edit 1: Plex running a TV show on the secondary screen works perfectly. I can work on the main screen while watching flawless video on the other.
Edit 2: As this display uses the CPU instead of the GPU I do notice a bit more fan activity than normal while watching video on the secondary monitor.