I know that I am late to this thread, but I agree that implementing a tagging system would benefit the site and its members greatly. I haven't read through the whole thread yet, but once I do, I will add any thoughts and ideas I have.
I think this is a fantastic idea. I do have a question, though - and I apologize if it's been asked already - but what would be the difference between "established characters" and "canon characters"? I can't think of any distinction that isn't just semantics, which I don't think would warrant two separate tags. Am I missing something there?