I am interested in those types of computers because I am insterested in robotics, and I think they have applications there, and because I think that using them you might be able to build your own laptop computer, which would be more flexible and less proprietary and less dependent on special drivers than a traditional branded laptop. One detriment for robotics was the cost; the type of robots I am thinking of should be cheap, almost disposable. For laptops these boards are often have an under powered CPU.
The main thing that caused me to by the Norhtec MicroClient Jr. was the price. It can be had for around $120.00. I paid close to $250.00 for my entire order, because I ordered two serial ports on the device and also two CF flash cards -- one is a blank 2 GB card for experimentation, the other is a 512 MB card with Puppy Linux pre-installed.
According to this more recent Linux Devices article, another company, E-Way Technology Systems, is now selling a computer that looks similar and is even cheaper and faster (except that my Norhtec actually seems to be 200 MHz, not 166 MHz as they advertised).
Security systems, monitor sensors and take pictures.
Environmental controls -- fancy house AC and heating, greenhouse control of vents/fans, etc.
Robots! Uses only a little battery power.
Routers -- modem, wireless
Backup server -- big disk attached to USB
If you have any ideas for a product that could be made using this device, please send me email.