[eluser]whitey5759[/eluser]
Don't most forums just show you a collection of recent posts, posts with alot of activity, and/or unanswered posts? If you are going to the extent of tracking who has read what, then the only logical way I can think of is to store a table with the user ID and post ID that have been read. If it's not in there, then it hasn't been read. Such a table might get alot of rows in it, but if your column types are numeric and indexed properly it will be lightening fast and not negatively affect the performance of your site.
