This will allow you to use /?range=a,e which will then return all posts with a post title that begins with an A,B,C,D,or E.

Wordpress - Range Filter on Post Title

public  function range_add($aVars) {
	$aVars[] = "range";
	return $aVars;
}
public  function range_where( $where, $args ) {
	if( !is_admin() ) {
		$range = ( isset($args->query_vars['range']) ? $args->query_vars['range'] : false );
		if( $range ) {
			$range = split(',',$range);
			$where .= "AND LEFT(wp_posts.post_title,1) BETWEEN '$range[0]' AND '$range[1]'";
		}
	}
	return $where;
}
add_filter( 'query_vars', array('atk','range_add') );
add_filter( 'posts_where' , array('atk','range_where') );