Hereunder you can find the plugin that EdB and Isaac pulled together for 0.9.x.
I loved that plugin, but I'm in no condition to turn that to the new plugin system.
For the coders among us, it will be a peace of cake, I'm shure.

For those up to a chalenge, it would be awsome, if we could edit this file (= add more links) through the backoffice.

<?php 
/**
 * This file implements the LinkWord plugin for b2evolution
 *
 * Automatic Linking of key words
 *
 * This hack is based ENTIRELY on Isaac's {@link http://isaacschlueter.com/} 
 * groovy AutoAcro plugin, and was converted to LinkWord by 
 * EdB {@link http://wonderwinds.com/}
 *
 * Scroll down to 'var $replacements' to add your own keywords and associated
 * URLs.  Keywords can be single words or phrases, but in order to be linked 
 * the text you type must match exactly what you have in here (case-sensitive).  
 * Keywords that are part of other tags will not be linked.  Keywords in your 
 * text must be preceeded and followed by non-alphanumeric characters.
 *
 * I suggest giving this a low priority number so that rendering happens early.
 *
 * Save this file as '_linkword.renderer.php' in your toolbars/renderers folder.
 *
 * b2evolution - {@link http://b2evolution.net/}
 * Released under GNU GPL License - {@link http://b2evolution.net/about/license.html}
 * @copyright b2evolution (c)2003-2004 by Francois PLANQUE - (@link http://fplanque.net/)
 * 
 * @package plugins
 * @subpackage renderers
 */
if( !defined('DB_USER') ) die( 'Please, do not access this page directly.' );

require_once dirname(__FILE__).'/../renderer.class.php';

class linkword_Rendererplugin extends RendererPlugin
{
	var $code = 'LinkWord';
	var $name = 'Link-A-Word';
	var $priority = 14;
	var $apply_when = 'opt-out';
	var $apply_to_html = true; 
	var $apply_to_xml = true;
	var $short_desc;
	var $long_desc;

	/**
	 * LinkWord array - this is where you set up your keywords and associated URLs
	 */
	var $replacements = array(
'b2evolution' => 'http://www.b2evolution.net/',
'b2evo' => 'http://www.b2evolution.net/', 
'b2e' => 'http://www.w3.org/',
'google' => 'http://www.google.com/',
'Hospitality Club' => 'http://www.hospitalityclub.org',
'Flickr' => 'http://www.flickr.com',
);
	var $search = array();
	var $replace = array();

	/**
	 * Constructor
	 * {@internal linkword_Rendererplugin::linkword_Rendererplugin(-)}}
	 */
	function linkword_Rendererplugin()
	{
		/**
		 * do you want links to open in new windows?  Some folk consider it rude, but
		 * some folk consider it okay.  Since I have links in posts open new windows
		 * I figured I better add the option to the plugin so's it would be what I
		 * want it to be.  Default is to NOT launch new windows.  Change to 'true' if
		 * you want to be rude and obnoxious to your visitors... like me.
		 */
		$new_window = true;

		foreach( $this->replacements as $k => $v ) {
			$this->link_search[] = '#(^|[^0-9A-Za-z>./:?!$_])(' . $k . ')([^0-9A-Za-z<:_])#';
			$this->link_replace[] = '$1<a href="' . $v . '">$2</a>$3';
			$this->linktitle_search[] = '#(<a href="[^"]*")(>)(' . $k . ')(</a>)#';
			if( $new_window ) {
				$this->linktitle_replace[] = '$1 title="' . $v . '" target="_blank"$2$3$4';
				} else {
				$this->linktitle_replace[] = '$1 title="' . $v . '"$2$3$4';
				}
			}
		$this->short_desc = T_('Automagically link to sites you like');
		$this->long_desc = T_('Words added to the plugin array will automatically be linked to the designated URL. Key words are case sensitive!  Key words must be preceeded and followed by a non-alphanumeric [0-9A-Za-z] character. Key words are checked to see if they are already enclosed by some other tag. Open up $blogurl/plugins/renderers/_linkword.renderer.php to edit the list of key words and their URLs.');
		}

	/**
	 * Perform rendering
	 * {@internal linkword_Rendererplugin::render(-)}} 
	 *
	 * @param string content to render (by reference) / rendered content
	 * @param string Output format, see {@link format_to_output()}
	 * @return boolean true if we can render something for the required output format
	 */
	function render( & $content, $format ) {
		if( ! parent::render( $content, $format ) ) { // We cannot render the required format
			return false;
			}
		$content = preg_replace( $this->link_search, $this->link_replace, $content );
		$content = preg_replace( $this->linktitle_search, $this->linktitle_replace, $content );
		// strip out tags within tags
		$content = preg_replace( '#(<[^<>]*)(<[A-Za-z]+[^>]*>)(.*)(</[A-Za-z]+>)([^<>]*>)#', '$1$3$5', $content);
		return true;
		}
	}

// Register the plugin:
$this->register( new linkword_Rendererplugin() );

?>