BuddyPress.org

Create your own theme… or copy and edit the default BuddyPress Theme:

header.php

<div id="my_userbar">

<?php include_once (TEMPLATEPATH . '/userbar.php'); ?>

<!--MY GOOGLE AD STUFF HERE-->

</div>

<?php include_once (TEMPLATEPATH . '/optionsbar.php'); ?>

Then just edit the css to format nicely