The following code leaves some extra space in front of the start of each box... nofirstindent should, I imagine, set it to 0 but it is not:
\documentclass{article}
\usepackage{tikz}
\usepackage{parcolumns}
\scrollmode
\begin{document}
\newcommand{\drawrect}[1]{\begin{tikzpicture} \draw (-1.5,-1.5) rectangle (1.5,1.5); \node at (0,0) {#1}; \end{tikzpicture}}
\begin{parcolumns}[nofirstindent,rulebetween,distance=0pt]{3}
\colchunk{
\drawrect{1}\\
\drawrect{2}\\
\drawrect{3}\\
}
\colchunk{
\drawrect{4}\\
\drawrect{5}\\
\drawrect{6}\\
}
\colchunk{
\drawrect{7}\\
\drawrect{8}\\
\drawrect{9}\\
}
\colplacechunks
\end{parcolumns}
\end{document}
It would also be nice if parcolumns would center itself between the margins.

\spaceskip-0.00001emright after\if@tempswato the nofirstindent macro removes the gap created. Not sure why it it works the way it does(basically adding -0 makes it align correctly even though it shouldn't do anything). – Uiy May 10 '12 at 04:21