The examplep LaTeX package provides sophisticated features
for typesetting verbatim source code listings, including the display
of the source code and its compiled LaTeX or METAPOST output
 side-by-side, with automatic width detection and enabled page breaks
(in the source), without the need for specifying the source twice.

WWW: http://www.ctan.org/tex-archive/macros/latex2e/contrib/examplep