\documentclass{art%ignore this}
icle}
\usepackage{url}
\begin{document}
\section{FooBar}\label{foo%ignore this too}
bar}
Methods~\cite{b1,%and, ignore, this, also}
b2}, by the {\em ab initio} crystal-orbital Hartree-Fock (HF) 
In section \ref{foo%same here}
bar}

\url{http://foo.com/dont%00ignore this}
and
\url$http://foo.com/dont%00ignore this$
However
\url%http://foo.com/dont% ignore this either

% Still a comment?

\def\host{foo.com}
Consider \verb%http://\host/page% versus \url%http://\host/page%.

Consider \verb%a_b% versus \url%a_b%.

When delimited, extra braces are allowed by verb, but not url.
\verb#{{{{# versus ?? % \url#{{{{{{#.
OTOH, neither allow extra braces when using braces.
%Consider \verb{{{{} versus %\url{{{{{{}.

\begin{thebibliography}{}
\bibitem{b1}{C. W. Bunn, Trans. Faraday Society 35 (1939)482.}
\bibitem{b2}{H. M. M. Shearer and V. Vand, 
Acta Crystallogr. 9 (1956) 379; H. M. M. Shearer and P. W. Teare, ibid.
12 (1959) 294. } 
\end{thebibliography}
\end{document}