WordPress.org

Author: NetWebLogic LLC

This plugin removes the admin bar completely from the public and admin areas of the website. Can be used either as a normal or MU plugin.

Upon activation/installation this works immediately. Nothing fancy, the admin bar is just not loaded anymore.

BuddyPress 1.1 Onwards

You can also add the following to your wp-config.php file and then you don't need this plugin ( sniff ;( ) :

define( 'BP_DISABLE_ADMIN_BAR', false );