The one I find really useful is
Replace all occurrences in the next 20 lines from the current line only. Great when your editing code and you've realised you used the wrong variable name in that method for example.
- ^V for block select
- Select the lines you want (10j for the next 10 lines)
- I for insert mode
- Type the # or whatever you want to prefix
:ret over highlighted text will reformat using the tabbing rules set up in your move up to the top line of the block to be delete
mm (sets a marker "m")
move down to the last line in the block
d`m (deletes to marker "m", and that's the grave below the tilde, not the back-quote)
Ah, add "set compatible" to your .vimrc file and you have 99% vi behavior.