List of active plugins on a Multisite installation.

multisite-plugins-activated.php

<?php
/*
Plugin Name: Multisite Plugins Activate
Plugin URI: http://www.damiencarbery.com
Description: List of active plugins on a Multisite installation.
Author: Damien Carbery
Version: 0.1

$Id: multisite-plugins-activated.php 3308 2016-01-20 11:04:27Z damien $
*/


// Based on: http://wordpress.stackexchange.com/a/54782/57684
// Updated to fix $wpdb->prepare warning and display plugin name.

/*
 * Multisite Dashboard Widget
 */
add_action('wp_network_dashboard_setup', 'wpse_54742_network_dashboard_setup');

function wpse_54742_network_dashboard_setup() {
    wp_add_dashboard_widget( 'wpse_54742_active_network_plugins', __( 'Network Active Plugins' ), 'wpse_54742_active_network_plugins' );
}

function wpse_54742_active_network_plugins() {
    /*
     * Network Activated Plugins
     */
    $the_plugs = get_site_option('active_sitewide_plugins'); 
    echo '<h3>NETWORK ACTIVATED</h3><ul>';
    foreach($the_plugs as $key => $value) {
        $plugin_data = get_plugin_data( WP_PLUGIN_DIR.'/'.$key );
        echo '<li>'. $plugin_data['Name'] .'</li>';
    }
    echo '</ul>';


    /*
     * Iterate Through All Sites
     */
    global $wpdb;
    $blogs = $wpdb->get_results("
        SELECT blog_id
        FROM {$wpdb->blogs}
        WHERE site_id = '{$wpdb->siteid}'
        AND spam = '0'
        AND deleted = '0'
        AND archived = '0'
    ");

    echo '<h3>ALL SITES</h3>';

    foreach ($blogs as $blog) {
        $the_plugs = get_blog_option($blog->blog_id, 'active_plugins'); 
        printf('<hr /><h4><strong>SITE</strong>: <a href="%s" title="Go to the Dashboard for %s">%s</a></h4>', get_admin_url( $blog->blog_id), get_blog_option($blog->blog_id, 'blogname'), get_blog_option($blog->blog_id, 'blogname'));
        echo '<ul>';
        foreach($the_plugs as $key => $value) {
            $plugin_data = get_plugin_data( WP_PLUGIN_DIR.'/'.$value );
            echo '<li>'. $plugin_data['Name'] .'</li>';
        }
        echo '</ul>';
    }
}