A CSS Framework
Mike Stenhouse's CSS Framework seems like it might be a good candidate for inclusion in AppFuse. In his article about this framework, he basically says that there are 6 basic layouts that "cover most of the blogs out there and most of the corporate sites as well". He shows you how it's possible to use a single XHTML page, and use CSS to achieve all of these layouts w/o changing your HTML. This is huge IMO because you can accomplish all the different layouts w/o changing your markup. Very cool. Hat tip to CSS Beauty.