This allows you to select some text using Vim's visual mode and then hit *
and # to search for it elsewhere in the file.  For example, hit V, select
a strange sequence of characters like "$! $!", and hit star.  You'll find
all other runs of "$! $!" in the file.

If you hit <leader>* ("\*" unless you changed the mapleader), vim will
recursively vimgrep for the word under the cursor or the visual selection.

Vim's default behavior is to just extend the visual selection to the next
word that matches the word under the cursor.  Doesn't seem very useful.

from http://got-ravings.blogspot.com/2008/07/vim-pr0n-visual-search-mappings.html


ALTERNATIVES

Just found visualstar: https://github.com/thinca/vim-visualstar
Looks like it uses a lot more code to do pretty much the same thing.
Is it better?

Also, godlygeek has this file: https://github.com/godlygeek/vim-files/blob/master/plugin/vsearch.vim
It's not an individually-installable plugin but it looks like it came from the same spot.