I'm wandering around the O'Reilly Open Source Convention (OSCON) this week. One of the neater things I've seen is
Inveneo. Basically really low power (wattage) boxes that can run off of 12 VDC.
These are deployed mostly in sub-Saharan Africa. Using local power (usually insulated by a deep cycle battery), solar, or generators. The desktop box only consumes 2-5 watts, the server (which can run a whole schoolroom of desktop) about 20 watts. The monitors are LCDs that run about 15 watts.
The specifications are interesting (I'd be happy with one of these in the kitchen), but it's more interesting because of the humanitarian/developing world implications. They also do a lot of setup like long distance WiFi, VOIP and other things as appropriate for people. So they're not just dumping these machines on them, but setting up an infrastructure for them that can be maintained.