Get a list of all blogs in a Wordpress mulisite installation with an image for each blog

functions.php

/*
 * This is kind of a hack but it gets the job done.
 * Paste this in your theme's functions.php
 * The function returns an array of all blogs in the multisite network.
 * For the image I make use of Wordpress' custom header functionality
 */
 
 function get_all_blogs() {
    $blogs = array();
    $count = 0;
    $blog_list = get_blog_list( 0, 'all' );

    foreach ($blog_list AS $blog) {

        $blogs[$count] = array();
        $blogs[$count]['id'] = $blog['blog_id'];
        $blogs[$count]['url'] = get_blog_option( $blog['blog_id'], 'siteurl' );
        $blogs[$count]['title'] = get_blog_option( $blog['blog_id'], 'blogname' );
        $blogs[$count]['text'] = get_blog_option( $blog['blog_id'], 'blogdescription' );

        // to access each blogs global settings
        switch_to_blog($blogs[$count]['id']);
        $data = get_theme_mod('header_image_data');
        $attachment_id = $data->attachment_id;
        $image = wp_get_attachment_image_src( $attachment_id, 'your_custom_image_size');
        $blogs[$count]['image'] = $image[0];
        restore_current_blog();

        $count = $count + 1;
    }

    return $blogs;
}