This code is the code needed to create a widget to show a list of all blogs. It is dependent on the plug-in List-All, that should be installed first. Create a blank text file named widget_list_all.php in your plugins folder, add the following php code. You should then be able to activate the List All plugin and the List-All-Blogs Widget on the plugins tab. Then look over in the presentation/widgets tab and you should have a new widget named List All Blogs Widget.

<?php
/*
Plugin Name: List-All-Blogs Widget
Plugin URI: http://codex.wordpress.org/WPMU_List_All_Blogs_Widget
Description: Creates a list of all blogs on a WPMU site as a widget, conversion from previous version based on code in http://www.erik-rasmussen.com/blog/2006/11/30/widgetize-anything/
Author: Unknown - last edited Angelo Bertolli
Author URI: http://codex.wordpress.org/WPMU_List_All_Blogs_Widget
Version: 0.0.2
*/

// $show_blog_list_widget = true;  // Uncomment this if you want this widget available for all users

function widget_list_all_blogs_init() {
        if ( !function_exists('register_sidebar_widget') )
                return;


        function widget_list_all_blogs($args) {
        extract($args);

        if(function_exists(list_all_wpmu_blogs)) {
                 echo $before_widget;

                 echo $before_title . 'All Blogs' . $after_title;
                        echo "<ul>\n";
                        list_all_wpmu_blogs('100', 'name', '<li>', '</li>', 'updated');
                        echo "</ul>\n";
                 echo $after_widget;
        }
                else
                {
                 echo "Error - function  list_all_wpmu_blogs not found";
        }
        }


    if ( function_exists('wp_register_sidebar_widget') ) // fix for wordpress 2.2.1
      wp_register_sidebar_widget(sanitize_title('List All Blogs' ), 'List All Blogs', 'widget_list_all_blogs', array(), 1);
    else
      register_sidebar_widget('List All Blogs', 'widget_list_all_blogs', 1);
}

if (get_blog_option(1,'siteurl') == get_settings('siteurl')) // Widget available for the main blog
        $show_blog_list_widget = true;

if ($show_blog_list_widget)
        add_action('plugins_loaded', 'widget_list_all_blogs_init');

?>