What are the dark corners of Vim your mom never told you about? [closed]

Answer 1

I just found this one today via NSFAQ:

Comment blocks of code.

Enter Blockwise Visual mode by hitting CTRL-V.

Mark the block you wish to comment.

Hit I (capital I) and enter your comment string at the beginning of the line. (// for C++)

Hit ESC and all lines selected will have // prepended to the front of the line.