Several PC 'facturers are creating ecological history by inventing "Good Enough" computers that are extremely efficient when used in the proper niche. Barring the standard marketing model (ahem, above), these models aren't the newest, fastest, or even latest tech. But, they are the best use of electrons for certain applications. And that's green, refreshing, and novel.
Exhibit A is the Eee PC line of sub-notebook computers from Asus. The basic model has a 2GB of solid-state Flash storage (which eliminates the spinning hard drive) and a wee 256MB of memory. More "advanced" models have simply more storage and memory, and maybe a camera and a bigger battery. The simple, brass tacks design is the green element here; this is simply what the on-the-go roadie needs to check email, surf the web, do a little Skype, check a few Wikipedia entries. They all come with Linux but will operate with Windows if you have to; the middle of the road model is around £219 including VAT.
Fit-PC is another offering from CompuLab, an Israeli company that manufactures low power systems. The CPU is a modest 500MHz AMD Geode LX800 and the entire system, including hard drive and 256MB of main memory, uses only 3-5W of total power. At those levels, you could use a foot treadle to run it. The Extreme Tech review is fair and balanced; this thing isn't going to leap tall mountains, and in fact some things one might take for granted - like viewing Flash-intensive web sites and having six windows open at once - noticeably slow the equipment. But form factor, power savings, and cost carry the day, particularly for applications that requires always-on usage and a light duty applications mix. It's $285. :: The Register :: Extreme Tech