I am setting up many forums on a site to filter the content in certain areas.  I really would like them all to link together but I dont want all the same posts on each one.  I want them dedicated to subjects which could be set as tags.

So what I believe would work with Live Forums is a mini forum module or setting that allows you to display all posts on the site that relate to a subject by tag.

Any posts made in this mini forum would automatically be tagged with the subject.

This could also be done with the other modules that have tag systems.