Hide widget titles by using an exclamation mark

hip_hide_widget_titles.php

<?php
/*
Plugin Name:  Hide Widget Titles!
Plugin URI:   
Description:  Prevent widget titles from displaying frontend by prepending them with an exclamation mark (ie. !Widget Title) 
Version:      1
Author:       Hippies
Author URI:   http://hippies.se/

**************************************************************************

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.

*************************************************************************
*/
add_filter( 'widget_title', 'hip_hide_widget_title' );
function hip_hide_widget_title( $widget_title ) {
  if ( substr ( $widget_title, 0, 1 ) == '!' )
  	return;
  else 
  	return $widget_title;
}