Hi,
I once saw this feature on emacs, and I've several times feel the need of it
while editing normal files, e.g. you copy from gnumeric or from an html table
and paste on gedit, now you only are interested on the third column data, you
can't select the text of the third column without selecting all the text before
and after that column.

This "column based selection" could be activated with some shortcut, e.g. SHIFT
+ CTRL + Mouse selection, will select in column-mode.

This could also be integrated by default in gedit instead of a plugin, I think
is a useful feature.