Mmh… Delicious cake

cake.tex

\documentclass[tikz]{standalone}
\begin{document}
\def\angle{0}
\def\radius{3}
\newcount\ind \ind=-1
\begin{tikzpicture}
  \foreach \percent/\name/\color in {
      46.6/Chrome/blue,
      24.6/Internet Explorer/red,
      20.4/Firefox/green,
      5.1/Safari/purple,
      1.3/Opera/orange,
      2.0/Other/yellow%
    } {
      \ifx\percent\empty\else                 % If \percent is empty, do nothing
        \global\advance\ind by 1              % Advance list index
        % Draw angle and set labels
        \draw[fill={\color!50},draw={\color}] (0,0) -- (\angle:\radius) arc (\angle:\angle+\percent*3.6:\radius) -- cycle;
        \node at (\angle+0.5*\percent*3.6:0.7*\radius) {\percent\%};
        \node[pin=\angle+0.5*\percent*3.6:\name] at (\angle+0.5*\percent*3.6:\radius) {};
        \pgfmathparse{\angle+\percent*3.6}    % Advance angle
        \xdef\angle{\pgfmathresult}           %   and store in \angle
      \fi
    };
\end{tikzpicture}
\end{document}