PurpleWiki is a wiki descended from UseModWiki
that adds granular addressability to the content of the wiki through a system called purple numbers. Each header, list or paragraph in a wiki page is given a unique identifier that can be used as an anchor in a URL. This is excellent for making reference. Alpha versions of PurpleWiki have generalized the parser so it can be used with blogs and as a document authoring system. An experimental version supports rudimentary transclusion of text from elsewhere in a wiki or blog into a page.
The latest version, adding support for pluggable viewers, transclusion and plugins for Movable Type and Bloxsom has been released. See http://www.blueoxen.org/tools/purplewiki/