Recently a client wanted all users to have a default user added to their buddy list.
The way they described it was "like Tom is added to MySpace users".
So, searching the issue queue revealed that this is an often asked for feature, but no out of the box solution existed.
Rather than make it into a feature for the base buddy list module, I chose to make it a contributed module, buddylistautoadd, that will be part of the tarball, but has to be explicitly enabled.
The module uses Drupal's AJAX autocomplete to list users, and the admin can select one of the to be auto added.
The latest 5.x tarball of the buddylist module has this module available.