BuddyPress 1.6 custom site avatars.

bp-custom.php

<?php

/*
  BuddyPress 1.6 custom site avatars.
  Add to (or create) /wp-content/plugins/bp-custom.php.
  Or place in theme's functions.php.
*/

/*
  Use a specific user's avatar for a site.
  Replace SITEID with the id of the site (find via Network Admin > Sites).
  Replace USERID (x3) with the id of a user whose avatar you want to use (find via Network Admin > Users).
*/

add_filter('bp_get_blog_avatar_SITEID', 'my_avatar_user_USERID');

function my_avatar_user_USERID () {
  echo bp_core_fetch_avatar (
    array(
      'item_id' => USERID,
      'type'    => 'thumb',
      'alt'     => 'SOME ALT TEXT',
      'width'   => 40,
      'height'  => 40,
      'class'   => 'avatar'
    )
  );
}

/*
  You can also just return the HTML of any ole image. HACK!
*/

add_filter('bp_get_blog_avatar_SITEID', 'my_avatar_SITEID');

function my_avatar_SITEID () {
  echo '<img src="http://mysite.com/path/to/avatar.jpg" alt="SOME ALT TEXT" class="avatar" width="40" height="40" />';
}