If you already know LaTeX, there is a quick and easy way to make images that you can paste into many different Windows applications such as PowerPoint.
For the following technique to work, it will be necessary to install MikTeX.
Now, if the details are not what you are interested in and you would like to get on with it, I have made files available. To get them to work the idea is simple. Download the files I have made available. Put them all in the same directory. Edit body.txt and double click the batch file (.bat). The body.txt file that I have provided contains the text:
$\frac{a}{b}$
Double clicking makeLaTeXImage.bat produces the image of the fraction 
The code is set up to produce images with a transparent background to make it conducive to pasting into documents with different colored backgrounds.
To change the image generated, change the text in body.txt
One modification to the images produced that I can anticipate an average user needing is a modification in the default resolution. This can be done by editing the following line of the batch file in your text editor:
dvipng -D 200 tmp.dvi -T tight -bg transparent
Here, 200 means 200 dpi. You can change this to whatever dpi you need. For instance,
dvipng -D 600 tmp.dvi -T tight -bg transparent
gives 600 dpi.
Details:
preamble.txt
\documentclass[12pt]{article}
\usepackage{amssymb}
\usepackage{color}
\usepackage{amsfonts}
\pagestyle{empty}
\begin{document}
This section contains the needed packages. You may have to modify it depending on the packages needed.
body.txt
$\frac{a}{b}$
This section contains the LaTeX text. You need to modify this file.
postamble.txt
\end{document}
This section contains the end of the document and is mostly irrelevant.
makeLaTeXImage.bat
copy /b /y preamble.txt+body.txt+postamble.txt tmp.tex
texi2dvi tmp.tex
dvipng -D 200 tmp.dvi -T tight -bg transparent
del /f /q tmp.aux
del /f /q tmp.dvi
del /f /q tmp.tex
del /f /q tmp.log
copy /b /y preamble.txt+body.txt+postamble.txt tmp.tex
/b copy in binary mode
/y copy without asking for confirmation
texi2dvi tmp.tex
This converts the TeX file to DVI.
dvipng -D 200 tmp.dvi -T tight -bg transparent
-bg transparent make the background transparent
-T tight Cropped to only include the equation with very little border.
-D 100 output resolution, 100 dpi
This generates tmp1.png which is where the image of the equation is stored.
Thank you very much, this saved me some time. I have a suggestion from the experience of using your script – because the dollar signs indicate inline latex, the fraction part shrinks to the height of stuff on the other side of an equal sign. Two solutions are 1) include package amsmath and use \dfrac instead of \frac, or 2) use \displaystyle after the first dollar. I tried to use \begin{equation} and \end{equation} in your preamble and postamble files, but this does not seem to work (complains about missing dollar), so the two solutions above seem best.