[WordPress] Offer filterable text strings in WordPress themes and child themes. Makes it easy to adjust original text, fully translatable. Example footer.php borrowed from _s (underscores) starter theme by @Automattic. http://glck.be/5740/

footer.php

<?php
/**
 * The template for displaying the footer.
 *
 * Contains the closing of the #content div and all content after
 *
 * @package _s
 */
$template_text = apply_filters( '_s_template_footer_text_strings',
	$strings = array(
		/* optionally use associative keys */
		__( 'http://wordpress.org/', '_s' ),
		sprintf( __( 'Proudly powered by %s', '_s' ), 'WordPress' ),
		sprintf( __( 'Theme: %1$s by %2$s.', '_s' ), '_s', '<a href="http://automattic.com/" rel="designer">Automattic</a>' ),
	),
	$strings );
?>

	</div><!-- #content -->

	<footer id="colophon" class="site-footer" role="contentinfo">
		<div class="site-info">
			<a href="<?php echo esc_url( $template_text[0] ); ?>"><?php echo $template_text[1]; ?></a>
			<span class="sep"> | </span>
			<?php echo $template_text[2]; ?>
		</div><!-- .site-info -->
	</footer><!-- #colophon -->
</div><!-- #page -->

<?php wp_footer(); ?>

</body>
</html>

functions.php

<?php
/**
 * Your _s child theme functions.php.
 * 
 * For sake of example only. Remember _s is made for hacking, not for child themes.
 *
 */
function _s_child_theme_setup() {

	load_child_theme_textdomain( '_s-child-theme', get_stylesheet_directory( . '/languages' );
}
add_action( 'after_setup_theme', '_s_child_theme_setup' );

/**
 * Filter text from footer.php
 */
function _s_child_theme_template_footer_text( $strings ) {

	$strings[1] = sprintf( 
		__( 'Super-proudly powered by %s', '_s' ), 
		__( 'WordPress and the good gods of the internet.', '_s-child-theme' ) 
	);

	return $strings;
}
add_filter( '_s_template_footer_text_strings', '_s_child_theme_template_footer_text', 2 );