If you open a text file in VI and see one big line with lots of '^M' where the line endings are supposed to be, use this command to fix it.
(Enter the the ^M by hitting ctrl-v and then the return key.)

:1,$s/^M/\r/g

Was importing a DB but wanted to prefix the tables, but the file was too large for TextMate. Here's all the vim substitutions

%s/DROP TABLE IF EXISTS `/DROP TABLE IF EXISTS `prefix_/g
%s/CREATE TABLE `/CREATE TABLE `prefix_/g
%s/INSERT INTO `/INSERT INTO `prefix_/g
%s/LOCK TABLES `/LOCK TABLES `prefix_/g
%s/ALTER TABLE `/ALTER TABLE `prefix_/g

within home directory, edit the .exrc file with set commands

the following sets numbered lines and auto indent.
Full listing of set commands available within by using :set all in vi

set nu
set ai

From one of the comments in http://www.vim.org/tips/tip.php?tip_id=689

:%s/word/&/g

The above substitutes "word" for itself, and tells you the number of substitutions made.

:se nu

To remove all "^M" characters from a file, open it in vi and use this command:

:%s/^M//g

The "^M" in the above line has to be typed in by pressing CTRL+v and then CTRL+M.