\documentclass{standalone}
\usepackage[miktex]{gnuplottex}
\usepackage{pgfplots}
\pgfplotsset{compat = 1.7}

\begin{document}

\begin{tikzpicture}

    \begin{axis}[
        %   title = {$x \times y$}
        , xlabel = $x$
            , ylabel = $y$
            , domain = -1:1
            , y domain = -1:1
        , enlargelimits
        , view = {0}{90}
        , x tick label style={
             /pgf/number format/.cd,
             fixed,
             fixed zerofill,
             precision=1,
             /tikz/.cd
            }
          , y tick label style={
             /pgf/number format/.cd,
             fixed,
             fixed zerofill,
             precision=1,
             /tikz/.cd
            }
        ]

\addplot3[contour gnuplot] {x*y};  
    \end{axis}

\end{tikzpicture}

\end{document}