Оно?
<!DOCTYPE html>
<html>
<head>
<script src="http://code.jquery.com/jquery-latest.js"></script>
<!--
<link rel="stylesheet" type="text/css" href="tmp.css" />
-->
<style type="text/css">
</style>
<script type="text/javascript">
$(document).ready(function (){
var url=$('span:contains("site3.ru")').prevAll('a').attr('href');
alert(url);
});
</script>
</head>
<body>
<a href="http://site.ru" target="_blank">лялялял</a>
<span class="5">
<a href="http://site2.ru">
<img class="6" src="//img.*************/phone.gif" alt="">
<span class="b-serp-url__link-text">Адрес и телефон</span>
</a>
</span><i class="7"></i>
<span class="8">site3.ru</span><i class="9"></i>
<span class="b10">Москва</span>
</body>
</html>