// Filter wp_nav_menu() to add profile link
add_filter( 'wp_nav_menu_items', 'my_nav_menu_profile_link' );
function my_nav_menu_profile_link($menu) {
global $bp;
$username = $bp->loggedin_user->userdata->display_name; // or 'user_nicename','user_login'
    if (!is_user_logged_in())
        return $menu;
    else
        $profilelink = '<li><a href="' . bp_loggedin_user_domain( '/' ) . '">' .  $username . '</a></li>';
        $menu = $menu . $profilelink;
        return $menu;
}