\documentclass{article}
\usepackage{setspace}
\usepackage{lipsum}
\onehalfspacing
\begin{document}
\title{merry setspace christmas test}
\author{who cares?}
\date{2011-12-19}
\maketitle

\section{dummy}
\lipsum[1]
\subsection{first offspring}
\lipsum[2]
\begin{tabular}{llr}
  a & silly & story about latex \\
  silly & a & story
\end{tabular}
\end{document}

%%% Local Variables: 
%%% mode: latex
%%% TeX-master: t
%%% End: 
