If you are looking for a certain symbol or its number and you already know the font name, the fonttable package prints its character table for you. You could compile this small example, printing the table of the psyr font:

\documentclass{article}
\usepackage{fonttable}
\begin{document}
\fonttable{psyr}
\end{document}

You will find the pdf output here.
Here is a part of the screenshot for a quick demonstration:

This topic was discussed on mrunix.de and on Matheplanet.