Administrators need to be able to permanently de-activate accounts that can't be re-activated with the original activation key. Likely this could be done using the level field.
On the login page (user.php), users need an option to re-send their activation key for those accounts not yet activated.
Administrators needs to be able to access/review/modify accounts that aren't yet activated without activating them. With the recent account spamming, our sites like to review new accounts without using the database and without activating them (because then the comment spam begins).
Finally, I think that we need two administrative notices for new accounts. The first would be when the account registration occurs. The second would be when the account is activated and use can occur. And notices for each could be deactivated as desires (although not recommended). Currently, the only way to deactivate is to make a dummy group with no-one in it and choose that group.