Q:

How to split a page in six equally sized sectors?

I'd like to split an A4 page into six equally sized sectors. I want that page to be in landscape. Each sector has a body of text and a caption.
I don't really have an idea where to start. I know I can split a page in to columns, but I need like six minipages, all equally arranged on one paper. The only idea I could come up with, is to use a0poster and then size it down for print. I think however, this is overkill; isn't there a better way to do that?
I'm preferably using XeLaTeX, if that is of any importance.

A:

You can use six minipages; I defined a \Block command using a minipage of the desired width and length with two arguments: the text and the caption (make the necessary formatting adjustments). I added some frames just for visualization purposes (and they will produce some overfull boxes); please delete the lines marked with %delete:
\documentclass{article}
\usepackage[landscape]{geometry}

\newcommand\Block[2]{%
\setlength\fboxsep{0pt}\setlength\fboxrule{0.1pt}% delete
\fbox{% delete
\begin{minipage}[c][.5\textheight][t]{0.333333\textwidth}
#1\par #2
\end{minipage}%
  }% delete
}

\begin{document}
\noindent
\Block{text}{caption}%
\Block{text}{caption}%
\Block{text}{caption}%
\par\nointerlineskip\noindent
\Block{text}{caption}%
\Block{text}{caption}%
\Block{text}{caption}
\end{document}

To meet the requirements in the comment:
\documentclass{article}
\usepackage[margin=3cm,centering,landscape]{geometry}

\newcommand\Block[2]{%
\setlength\fboxsep{0pt}\setlength\fboxrule{0.1pt}% delete
\fbox{% delete
\begin{minipage}[c][\dimexpr.5\textheight-2pt\relax][c]{\dimexpr0.3333333\textwidth-3pt\relax}
\centering
#1\par #2
\end{minipage}%
  }% delete
}

\begin{document}
\thispagestyle{empty}% optional: suppress page numbering

\noindent
\Block{text}{caption}\hfill%
\Block{text}{caption}\hfill%
\Block{text}{caption}%
\vfill
\noindent\Block{text}{caption}\hfill%
\Block{text}{caption}\hfill%
\Block{text}{caption}
\end{document}

Using some of the options for the geometry package, the text area layout can be modified at will.

A:

Here's a solution using the pdfpages package. It consists of two steps: First you produce a document with a small paper size, and then you produce another document that combines these small pages onto one A4 landscape page.
This is your actual document, where you put all of your text etc. You might have to adapt the margins, page numbers, etc. to your needs.
% This file is called sixpages-doc.tex
\documentclass{article}

\usepackage[paperwidth=9.9cm,paperheight=10.5cm]{geometry}
      % paperwidth is A4/3, paperheight is A4/2

\usepackage{lipsum}% just for filler text

\begin{document}
\lipsum[1-6]
\end{document}

This is the document that puts the six pages on one page:
\documentclass{article}

\usepackage[landscape,a4paper]{geometry}
\usepackage{pdfpages}

\begin{document}
\includepdf[pages=-,nup=3x2]{sixpages-doc.pdf}
    % pages=- means all pages
    % nup "Puts multiple logical pages onto each sheet of paper. The syntax of
    %  this option is: nup=⟨xnup⟩x⟨ynup⟩." (from the manual)
    % If you want this layout:
    % 1 3 5
    % 2 4 6
    % use the option "column".
\end{document}

This is the output of the second document:

A:

I know that you want to use minipages. But here is a version using \parbox. You can't have certain things like footnotes here. This answer is given just to complete the list.
We ride on Gonzalo's code (thanks @Gonzalo) and modify a bit:
\documentclass{article}
\usepackage[landscape]{geometry}

\newcommand\Block[2]{%
\setlength\fboxsep{0pt}\setlength\fboxrule{0.1pt}% delete
\fbox{% delete
\parbox[c][.5\textheight][t]{0.3\textwidth}
{#1\par #2}
%
  }% delete
}

\begin{document}
\noindent
\Block{text}{caption}\hfill
\Block{text}{caption}\hfill
\Block{text}{caption}%
\vfill\noindent
\Block{text}{caption}\hfill
\Block{text}{caption}\hfill
\Block{text}{caption}
\end{document}

