hide all instances usernames except for admins/mods?

I want to run a board where people can register, but their username never shows up when they post (they could put a signature at the bottom of their post if they want).  I'm doing ok on the main forum list with getting rid of the "Posted by" usernames, but I'm running into difficulty in the topic lists and topics themselves.  Any ideas?

Let me be a little more specific...

I want users to be able to log in and post like normal.  Users should not be able to see the usernames of anyone who posts except for admins or moderators.  Moderators/admins should be able to see everyone's usernames at all times.  Essentially, I want an anonymous board from the point of view of the users with the mods/admin being able to see who is posting what.

Thanks,

Ct

Getting there... if anyone is interested, I'll be happy to share.