cschmitt

OK, five minute job. No error checking, no styling, no nothing.
Use at your own risk.
Create a new file displaypost.php in your wp-content/plugins directory.
Paste the code below into it.
Activate the plugin.
Drag the widget to your sidebar.
Enter the desired post ID and Bob’s your uncle (I always wanted to use that phrase :))

Cheers,
Christian

<?php
/*
  Plugin Name: Display Post
  Plugin URI: http://localhost/wordpress
  Description: Display the content of a single post in a widget.
  Author: Christian Schmitt
  Version: 1
  Author URI: http://localhost/wordpress/
 */

class DisplayPost extends WP_Widget
{
    function DisplayPost()
    {
        $widget_ops = array('description' => "Display the content of a single post in a widget.");
        $this->WP_Widget('displaypost', 'Display Post', $widget_ops);
    }

    function widget($args, $instance)
    {
        extract($args);
        $postId = $instance['postid'];
        $thePost = get_post($postId);
        echo $before_widget;
        echo $before_title . $widget_name . $after_title;
        echo $thePost ? $thePost->post_content : "Invalid post ID!";
        echo $after_widget;
    }

    function update($new_instance, $old_instance)
    {
        $new_instance = (array) $new_instance;
        $instance['postid'] = strip_tags($new_instance['postid']);
        return $instance;
    }

    function form($instance)
    {
        $instance = wp_parse_args((array) $instance, array('postid' => -1));
        $postid = esc_attr($instance['postid']);
?>
        <p>
            <label for="<?php echo $this->get_field_id('postid'); ?>">Post ID</label>
            <input type="text"
                   class="widefat"
                   id="<?php echo $this->get_field_id('postid'); ?>"
                   name="<?php echo $this->get_field_name('postid'); ?>"
                   value="<?php echo $postid; ?>" />
        </p>
<?php
  }

}

function displaypost_init()
{
    register_widget('DisplayPost');
}

add_action('widgets_init', 'displaypost_init');

?>

Quick and dirty…

I added these lines to NextGEN Gallery’s stylesheet:

.ngg-gallery-thumbnail-box { display:none; !important;}
#ngg-image-1 {display: block; !important;}

This hides every thumbnail but the first.

Hope this helps.

Cheers,
Christian