iirc there is an #emacs mode which draws a line from the top to the bottom of the screen to the bottom of the screen and the column on the cursor. Like hl-line-mode, but rotated 90 degrees.

What is this mode called? 

 found it: it's called vline-mode

now back to lining up columns :D

https://media.emacs.ch/media_attachments/files/111/082/843/884/331/383/original/61aad2ffa8ab7bd5.png