But not bumping a thread you post in? Why would you post something that you know no one would ever read?
I can see how this could allow trolls to take an extinct thread, and start saying things behind people's backs.
I guess I didn't think about that...I was thinking it might just be nice for newer members to be able to add to the conversations about old episodes without necessarily bumping 3-year-old threads. I suppose that it could be set up that it would still notify the previous posters that there's a new reply in the thread - I was just more concerned with not bumping a long-dead thread just to make a joke or something, but I guess I can also see the wisdom in saying that "if it's not worth bumping the thread, it's not worth posting."
As far as Karma/rep/thanks, I've seen similar systems, but I rather prefer the ones that don't have a "thumbs down" option, but just the option to mark/compliment the posts that are good. But yeah, it looks like such a system has already (more or less) been tried out and rejected.