nonsense, but useful nonsense:
if you have tags working, cd into the directory with the tags and hit something like:
vim -t env_alloc
vim will automatically open to the file with that symbol. Nice.
Other nonsense:
:ab #d #define
vim abbreviations, make it so whenever you type #d it will be replaced by #define
you can actually execute a proper shell from vim, just use the :shell command.
finally, there is a “confirm” option for the substitute command, so:
%s/foo/bar/gc will globally replace foo with bar and confirm each replacement.