\documentclass{article}
\usepackage[a4paper,nohead,nofoot,margin=0mm]{geometry}
\usepackage{multido}
\usepackage{color}
\usepackage[latin1]{inputenc}
\definecolor{Background}{rgb}{0.7,0.7,0.9}
\pagecolor{Background}
\newcommand*{\FirstFont}{\fontsize{18}{20pt}\sffamily}
\newcommand*{\SecondFont}{\fontsize{12}{14.4pt}\sffamily}
\newcounter{column}\setcounter{column}{0}
\newcommand*{\columnn}{3}

\newcommand*{\Karte}[2]{%
  \parbox[c][3cm][c]{6cm}{\centering%
    {\FirstFont #1\par}%
    {\SecondFont #2\par}%
  }%
  \stepcounter{column}
  \ifnum\value{column}=\columnn\relax
    \par
    \setcounter{column}{0}%
  \fi%
  \ignorespaces
}
\setlength{\parindent}{0pt}

\begin{document}
\multido{\n=1+1}{24}{%
	\Karte{Dr.-Ing. Herbert Voß}%
		{Wasgenstr.21\\D-1000 Berlin\\[1ex]Tel.: 030-11223344}%
}
\end{document}