I'm a board member of YesLogic, the company that makes the Prince formatter. Prince is a
fantastic product for creating PDF documents. Most of the documents in
this world should reside on the web and never end up in a PDF file.
However, sometimes you want to fixate information (e.g., for printing
or archiving) and in these cases you want a flexible tool for
generating PDF using web standards. The latest edition of a book I co-authored on CSS is typest using Prince. I'm also the CTO of Opera.