Scribble is a collection of tools for creating prose documents – papers, books, library documentation, etc. – in HTML or PDF (via Latex) form. More generally, Scribble helps you write programs that are rich in textual content, whether the content is prose to be typeset or some other form of text to be generated programmatically.
This document itself is written using Scribble. At the time that it was written, its source was available at http://svn.plt-scheme.org/plt/trunk/collects/scribblings/scribble/ starting with the "scribble.scrbl" file.