CheckDoc checks your EmacsLisp code for errors in documentation and style.
Running CheckDoc is a must before posting to gnu.emacs.sources or uploading to the ElispArea.
The homepage is http://cedet.sourceforge.net/checkdoc.shtml

checkdoc.el is part of GNU Emacs since version 21.
Here are some things extending checkdoc,
;;;###autoload on at least one entrypoint commandKeyword: known to FinderModeURL `http://...' for buttonizing docstrings