I wish I'd known basic visual block mode stuff earlier. Even if you don't use VIM for anything else, it can be a big time saver to open up a file in VIM just for some block operations. I'm quite sure I wasted a ton of time doing this kind of thing manually.
Examples I've found particularly useful, when, say, refactoring lists of symbolic constant names consistently:
Enter Visual Block mode (Ctrl-Q for me on Windows instead of Ctrl-V)
Move cursor to highlight the desired block.
Then, I whatever text and press Esc to have the text inserted in front of the block on every line.
Use A instead of I to have the text inserted after the block on every line.
Also - simply toggling the case of a visual selection with ~ can be a big time saver.
And simply deleting columns, too, with d of course.