I am however curious how "An optional confirmation screen displaying similar threads by keywords before a user creates a new thread. This would prevent duplicate threads." will work; could you please elaborate?
This feature actually exists on Airliners.net's custom forum software. Before confirming to create a new thread, a page displaying a list of similar threads is shown. This prevents users from creating duplicate threads.
Perhaps Ian's idea is good too, however, some sites only allow moderators/admins to delete threads if they are duplicates. I know that vBulletin features this, however, my idea actually prevents creation of duplicate threads BEFORE being posted.
