I have an idea (no code though) that might help in this situation.
Perhaps if there were a mod that would allow registered users to post anonymously. The "Allow Anonymous Posting Mod" (theoretical title) could be turned off/on for each category/forum/topic much like subscriptions.
When a user posts, he could check a box to post anonymously. The database would still hold his ID but it shows up as "ANONYMOUS" on the board. Also, perhaps admins can view the alias of those who post anonymously.
This would still provide anonymous posting but also provide for some accountability because it requires that you be a registered user.
Just a thought.
Bookie
"May the forces of evil become confused on the way to your home." - George Carlin