I'm using Domain Access module (http://drupal.org/project/domain) for running few very similar sites out of single Drupal 6 installation/database.

What I need is to have slightly different menus between those sites.

Generally, most items will be exactly the same throughtout all domains, on some of them though I don't want specific items to be displayed (for example, maybe later there would be other requirements too).

Haven't found any module offering such functionality, so considering other options now.

Simplest and easiest solution would be to hide them using CSS, but definitely this is not a good solution.

hook_menu_alter was disqualified as well, for quite obvious reasons.

What I'm thinking about right now is doing it from theme_menu_item() / theme_menu_item_link() level. Haven't looked yet into possibility of basing it on (something like) node access permissions (which actually would mean writing own module for this), going to do it as well, but meantime perhaps someone could suggest even different approach?