Thanks to all, 0install.net is exactly what I am looking for. One thing is that this system is "per user". Having something like that "per computer" would be nice. That is, the admin sets up the computer with _all_ packages and the user can use _all_ packages. (Except that _not_ all packages are installed).
Thanks, Gonsolo -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]