Product Tag List Widget for WooCommerce by Webbgaraget.

product-tag-list-for-woocommerce.php

<?php
/**
 * Plugin Name: Product Tag List Widget
 * Plugin URI:
 * Description: A sidebar Widget for displaying the product tags in a list.
 * Version: 1.0
 * Author: Webbgaraget
 * Author URI: http://www.webbgaraget.se
 * Tags: plugin, product, tag, list, widget
 * License: GPL
 */

/* Add our function to the widgets_init hook. */
add_action( 'widgets_init', array('Tag_List_Widget', 'register_widget') );

class Tag_List_Widget extends WP_Widget {

	/* Function that registers our widget. */
	public static function register_widget() {
		register_widget( 'Tag_List_Widget' );
	}

	public function __construct() {
		/* Widget settings. */
		$widget_ops = array( 'classname' => 'tags-list', 'description' => 'A widget that displays a list with the product tags.' );

		/* Widget control settings. */
		$control_ops = array( 'width' => 300, 'height' => 350, 'id_base' => 'tags-list-widget' );

		/* Create the widget. */
		parent::__construct( 'tags-list-widget', 'Product Tags List Widget', $widget_ops, $control_ops );
	}

	// Widget output
	public function widget( $args, $instance ) {
		global $post;
		extract( $args );

		/* User-selected settings. */
		$title = apply_filters('widget_title', $instance['title'] );

		/* Before widget (defined by themes). */
		echo $before_widget;

		if ( $title ) echo $before_title . $title . $after_title; ?>

		<?php

		$terms = get_terms( 'product_tag');

		if ($terms) { ?>
			<select id="artists" name="artists">
				<option value="">Select artist</option>
			<? foreach ($terms as $term) { ?>
				<option value="/artist/<?php echo $term->slug; ?>"><?php echo $term->name; ?></option>
			<?php } ?>
			</select>
		<?php }

		/* After widget (defined by themes). */
		echo $after_widget;
	}

	public function update( $new_instance, $old_instance ) {
		$instance = $old_instance;

		/* Strip tags (if needed) and update the widget settings. */
		$instance['title'] = strip_tags( $new_instance['title'] );

		return $instance;
	}

	// Widget in admin area
	public function form( $instance ) {

		/* Set up some default widget settings. */
		$defaults = array( 'title' => 'Artists' );
		$instance = wp_parse_args( (array) $instance, $defaults ); ?>

		<p>
			<label for="<?php echo $this->get_field_id( 'title' ); ?>">Title:</label>
			<input id="<?php echo $this->get_field_id( 'title' ); ?>" name="<?php echo $this->get_field_name( 'title' ); ?>" value="<?php echo $instance['title']; ?>" style="width:80%;" />
		</p>

		<?php
	}
}
?>