Cut the text after a specific number of characters. If the max length is not reached, just output the text without modifications.

app_code_local_[Namespace]_[ModuleName]_Helper_Data.php

<?php
/**
 * Namespace ModuleName
 *
 * @category    Namespace
 * @package     Namespace_ModuleName
 * @copyright   Copyright (c) 2015 Tobias Forkel (http://www.tobiasforkel.de)
 * @license     http://opensource.org/licenses/osl-3.0.php Open Software License (OSL 3.0)
 */

class Namespace_ModuleName_Helper_Data extends Mage_Core_Helper_Abstract
{

    /**
     * Cut the text after a specific number of characters.
     * If the max length is not reached, just output the text without modifications.
     * 
     * If a word is longer then the max length, it will not work properly. Please extend this method
     * to support strings without spaces.
     *
     * @param string $string Any kind of string.
     * @param integer $maxlength The max length to output.
     *
     * @return string
     */
    public function truncateText($string = '', $maxlength = 10)
    {
        return strtok(wordwrap($string, $maxlength, ' ...\n'), '\n');
    }
}