Today i came head to head with one of the most peculiar cases. I had to make a table in LaTeX and the decimal colums to be aligned in the ".". I searched a little in and i found the following solution:)
\begin{tabular}{ c r@{.}l r@{.}l }
& \multicolumn{2}{c}{Column 1} & \multicolumn{2}{c}{Column 2}\\
Data 1 & 3&505 & 33&832\\
Data 2 & 3&505 & 33&832\\
\end{tabular}

The trick is that you actually have two columns separated by a dot (".") aligned right and left. The good thing is that you dont need any optional package (very handy when you write publications and want your editor to use the source tex :) ).