The One Laptop per Child web site is very pleasing to look at and navigate as well as being informative. It is the antithesis of a busy web site. The home page is deceptively simple. All you see is the iconic message on the left and the title of the site in the upper left. The icons spell out "One Laptop per Child" as you look at them left to right, so this would be how it establishes its "brand." But then upon mousing over them you see that the icons are the central navigation for the site as a word appears below representing that page's content. Clicking on one of them brings you to one of four sections (vision, laptop, participate, children).
Visual consistency is achieved as the iconic message/navigation is maintained on each sub-page and used for the site navigation throughout. Aside from the site title in the corner the rest of the page is white, so this phrase establishes its central importance very quickly by being right up front and center. The message is visually engaging as well with its dramatic color scheme, featuring highly saturated primary colors and one secondary color. The colors aren't in their pure form, though, so the yellow is more of a goldenrod, the green more grassy green, the blue a sky blue, and the red edging toward pink. I believe they were carefully chosen, because this makes them more interesting to the eye and (at least to me) they have a calming effect rather than the brash feeling pure primary colors would have. The color palette is maintained throughout the website as each section keeps the main color of its navigation icon. The web site layout is bounded by vertical lines that separate sections of text from each other and imply a rectangular boxy structure without being heavy-handed. The layout also achieves a kind of consistency in structure by separating the text sections with the vertical lines in the same way the icons on the front page and in the navigation are separated. Thus the visual flow is left to right as you look across the main sections in each sub-page.
Overall, I think the site's pleasant and simple appearance really facilitates a positive feeling in the user and makes them happy to be getting the information from the site. There is a lot of good information, so I'm glad the site's design facilitates it's dissemination well.