For debugging WP rewrite rules

display-rewrites.php

<?php

function jb_show_rewrite_rules() {
	$rules = get_option('rewrite_rules');

	$n = 0;
	$html = '<table><tr><th style="width: 5%;">#</th><th style="width: 35%;">Key</th><th style="width: 60%;">Rule</th></tr>';
	foreach ( $rules as $key => $value ) {
		$html .= '<tr><td>' . ++$n . '</td><td>' . $key . '</td><td>' . $value . '</td></tr>';
	} // end foreach
	$html .= '</table>';
	echo $html;
}

// Something like this for quick and dirty
add_action('wp_head', 'jb_show_rewrite_rules');

// Or run the funtion where you want to see the data