The purpose of this role is take a string and turn it into a friendly string to search engines.

function friendly_url($url) {
    $url = strtolower($url);
    $find = array('á', 'é', 'í', 'ó', 'ú', 'ñ');
    $repl = array('a', 'e', 'i', 'o', 'u', 'n');
    $url = str_replace($find, $repl, $url);
    $find = array(' ', '&', '\r\n', '\n', '+', '/');
    $url = str_replace($find, '-', $url);
    $find = array('/[^a-z0-9\-<>]/', '/[\-]+/', '/<[^>]*>/');
    $repl = array('', '-', '');
    $url = preg_replace($find, $repl, $url);
    return $url;
}

$url = "this is a test";
echo "http://www.mysite.com/".friendly_url($url); //"http://www.mysite.com/this-is-a-test"