How to Add WYSIWYG Editor (tinyMCE) to plugin options page compatible with WordPress 3.0 and up?

Pre WP 3.3:
http://www.dev4press.com/2010/tutorials/wordpress/tips/add-rich-text-editor-to-your-plugin/

If you are using WP 3.3 or later you might look up wp_editor:
http://codex.wordpress.org/Function_Reference/wp_editor

$settings = array(
    'teeny' => true,
    'textarea_rows' => 15,
    'tabindex' => 1
);
wp_editor(esc_html( __(get_option('whatever_you_need', 'whatever'))), 'terms_wp_content', $settings);