Atlassian should give out t-shirts to people who suggest the most useful enhancements that get ignored for the longest time. This one would be close!

I would love to see this or have a way to remove them from the People Directory so they can't be searched. It would really clean up my people directory.

In a corporate environment like ours, with employers and sub-contractors coming and going all the time, feature like this would be very very useful indeed. Please consider implementing a way to purge all traces of a certain account from Confluence but still leaving the content created by removed accounts intact (except for references to the original creator, of course)-

This feature is a must have. When a member leaves an organization, the account should be removed. Changing the password will not suffice.
Imagine the following scenario:
Employee Y leaves Company X for a position with Company Z.
Administrator A changes the password so the departing employee can't log in anymore.
The next day the employee contacts administrator B and asks her to change the password.
Administrator B Changes the password and the employee can access the wiki until the end of days, suppling Company Z with all kinds of useful information about Company X stored in the company wiki. (OK, I admit, I'm paranoid, but still, its a realistic scenario)