Anything skin-related or having to do with how page elements are displayed

Skins /
SkinChange  change skin via query or cookie setting (Stable)
SkinConfig  Define interactively (via a wiki page) the main parameters of a skin
SkinGuidelines  A set of tips for skin design and packaging skins for distribution (Stable)
TestPageDirectives  Tool for easy testing of your skin under various directives (stable)