Not to brag or anything, but I read that my EEE PC uses about the same amount of energy as a CFL lightbulb. Pretty impressive. It's also basically made me paperless since it's a lot nicer to carry than a bunch of paper notebooks and textbooks.
Small is beautiful. It uses a simple form of Linux instead of bloated Windows. I'm always finding a new use from a phone alternative (Skype) to an electronic recipe book small enough to not hog my kitchen counter.
I try not to buy new computers too often though because of the impact of manufacturing and later, recycling difficulties. So I like that it doesn't have a lot to break, like the CD drive that broke in my last laptop. Buying an external anything from a Lacie Harddrive for more space or a CD burner is a lot easier than replacing them inside a laptop. Plus an external hard drive is subject to a lot less heat stress, so usually they last a lot longer.