How to list all custom post types in a custom widget?

Figured out how (Thanks to WordPress Codex):

    /** @see WP_Widget::widget */
    function widget($args, $instance) {
        extract( $args );
        $title = apply_filters('widget_title', $instance['title']);
        ?>
              <?php echo $before_widget; ?>
                  <?php if ( $title )
                        echo $before_title . $title . $after_title; ?>
                    <?php // Create and run custom loop
        $custom_posts = new WP_Query();
        $custom_posts->query('post_type=page_content');
        while ($custom_posts->have_posts()) : $custom_posts->the_post();
    ?>
            <h2><a href="https://wordpress.stackexchange.com/questions/8694/<?php the_permalink(); ?>" title="<?php printf( esc_attr__( 'Permalink to %s', 'twentyten' ), the_title_attribute( 'echo=0' ) ); ?>" rel="bookmark"><?php the_title(); ?></a></h2>
    <?php endwhile; ?>

              <?php echo $after_widget; ?>
        <?php
    }

    /** @see WP_Widget::update */
    function update($new_instance, $old_instance) {
    $instance = $old_instance;
    $instance['title'] = strip_tags($new_instance['title']);
        return $instance;
    }

    /** @see WP_Widget::form */
    function form($instance) {
        $title = esc_attr($instance['title']);
        ?>
            <p><label for="<?php echo $this->get_field_id('title'); ?>"><?php _e('Title:'); ?> <input class="widefat" id="<?php echo $this->get_field_id('title'); ?>" name="<?php echo $this->get_field_name('title'); ?>" type="text" value="<?php echo $title; ?>" /></label></p>
        <?php
    }

} // class FooWidget

// register FooWidget widget
add_action('widgets_init', create_function('', 'return register_widget("FooWidget");'));