There is no default vbulletin option you may turn on that will force a user to use tags.

Would it be possible to make a mod do that?

I would guess so. You can make a mod to do just about anything.

Just curious.. Anyway the tags can be automatically added? I don't believe there is such a plugin for vb4 yet.

Sure there are ways to automatically add tags to your thread, but as I said above, this is not the mod for that.

I've been looking for something like this for 3.8x, does anyone know of this being available?

I was wondering if it would be possible for you to add predefined tags on a forum to forum basis (Making it so each forum could have its own predefined list, so they won't carry over to non-related forums).

Not the way it is currently set up. You could easily modify it to do so though by just defining the array of terms within the plugin and just using a condition - if forumid x, then use this array, else use that array.

Just in case you'll want to spend some time on this mod ... :D
It would be beautiful if this mod could work in "new thread" as well.

You beat me to it :)

This is a great mod but just seems to be set up wrong. The list only appears once the thread is posted which by then its too late members have submitted their own, sometimes wrongly spelt tags

Is there any way to make the predefined tag list show up when posting a new thread therefore allowing members to select tags from the list before submitting the thread