How to create alternating rows in a table?

You can use the features of the colortbl package with additions of xcolor. See code below for a small example.

\documentclass[11pt,a4paper]{article}
\usepackage[T1]{fontenc}
\usepackage[latin1]{inputenc}
\usepackage[table]{xcolor}    % loads also »colortbl«

\begin{document}
  \rowcolors{2}{gray!25}{white}
  \begin{tabular}{cc}
    \rowcolor{gray!50}
    Table head & Table head\\
    Some values & Some values\\
    Some values & Some values\\
    Some values & Some values\\
    Some values & Some values\\
  \end{tabular}
\end{document}

The particular package manuals have the details.

This can easily be achieved using xcolor. It is explained at Wikibooks, you just add the table option to \usepackage{xcolor} and in the table itself you put

\rowcolors{1}{color-1}{color-2}

One thing that might be worth pointing out, is that apparently, many packages call on xcolor, and I had endless clashes first time I tried it, and it took me such a long time to figure this one out, so I felt it might help someone as slow as me to mention this: The xcolor package should be loaded last (or at least after the clashing packages).