Q:

Is it possible to multiply the x coordinates of a plot by a certain factor using pgfplots

I have a pgf plot.  Now the scale on the x-axis is at the moment frequency, hz, but it should be rad/s to save myself time exporting the file again is it possible to multiply the x-coordinate of every data point with a certain factor easily in pgf plots?  In this case 2*pi? 

A:

use x expr as in 
\addplot table[x expr=\thisrowno{0}*2*pi, y index=1] {\table};

assuming that your abscissas are stored in the first column of a table
loaded in the macro \table and your ordinates in the second. 
More details are given on page 29 of the pgfplots manual. 

A:

Yes it is!  From the pgfplots manual:
\documentclass{standalone}
\usepackage{pgfplots}
\begin{document}
    \begin{tikzpicture}
    \begin{axis}[
    xtick={0,1.5708,...,10},
    domain=0:2*pi,
    scaled x ticks={real:3.1415},
    xtick scale label code/.code={$\cdot \pi$}]
    \addplot {sin(deg(x))};
    \end{axis}
    \end{tikzpicture}
\end{document}

The option of interest is the scaled x ticks={real:3.1415}, which tells pgfplots to scale the x values by a factor of 3.1415.  You can switch off the "times PI" part below the axis by removing the xtick scale label code/.code={$\cdot \pi$} code.