here is one example.
http://www.linuxfordevices.com/c/a/News ... 10/?kc=rss
so it is for the experienced builder of such things. And one would still need a screen that draw as little as possible and still give readable result.1GHz SoC touted for single-Watt consumption
By Eric Brown
2010-04-26
Development platforms are available, built around a baseboard that supports both the Armada 310 and Armada 300, says Marvell (see image above). Complete reference design platforms are said to be available for Linux, VxWorks, and BSD, including software drivers and board support packages (BSPs).
No information was available of real-world ports and other features, however.
The lady that made the screen to the olp she seems to have something going but I have no link just now. No backlight was one trick she planned to use to make it look great in bright sunshine. That would save on battery. The better light in the room the better the screen looks? Now it is the opposite. The best sunshine and one see nothing on the screen. Ambient light outperform the backlighted screens.
Edit
one watt? what is that?
Well suppose you have a lcd battery typical for a Mobile Phone. 3.7 Volt and the comptuer draw one watt.
1/3.7=0.27Amps and if the battery is a typical Nokia litium then say 700mA to 1400mA then approx 2.5 hours to 5.2 hours. So mobile batteries are two small for running many days. One would preferably go NiMH AA cells that can be easily bought and replaced and one could even use discarded such in parallel if one want to save money.