LaTeX.org

Great! Thanks a lot, Stefan.

I and my friends have lengthy (lecture and reading)notes which make extensive use of newcommand. I wanted to convert those docs to wordpress to make them public and collaborative. We found a tool (http://lucatrevisan.wordpress.com/latex-to-wordpress/) that converts latex to wordpress code, but as an ...

Yes.
It would be great if I can somehow get the 'final' source file, in which all the occurrences of the old commands are replaced as I have described in the newcommand. Is there an easy way to do this?

Clarification:

I want to automatically replace all appearances of <my input to new-command eg.\ket{bla}> in your source with <the replaced code (as a result of newcommand) eg.\left|bla\right>)

Is there a way to do this?

Yes, that is what I have in mind: I want to automatically replace all appearances of \ket{bla} in your source with \left|bla\right>. Is there a way to do this?

ps: Thanks for the information about the braket package.

I use the following:
\newcommand{\ket}[1]{\left| #1 \right>} % for Dirac bras
instead of typing \left| ket-text \right> every time.

But, for some purpose, I want my tex file in the format with the replaced commands; i.e. tex code that I would have written had I not known about \newcommand at all ...