With the new 2.3 release WordPress supports a native tagging system for posts. This plugin allows you to insert tags to pages too and not only to posts.
Usage
When you activate the plugin it just works adding the tags field to the page editing form. Fill it with the tags you want in each page. To view the tags in your blog you have to add the WordPress function to your themes, please refer to the documentation page for more information (https://codex.wordpress.org/Template_Tags/the_tags).
Infos
You could find every informations here and much more at http://www.michelem.org/wordpress-plugin-tags4page/