public function setData($key, $value=null)
{
    if(is_array($key)) {
        $this->_data = $key;
    } else {
        $this->_data[$key] = $value;
    }
    return $this;
}

Mage::log("Some message about which function you are in ".$someHelpfulVariable, null, 'mylogfile.log');