I think this would be great, especially as an option. The posts that generate the most discussion are often interesting, and curiously aren't always the top voted.
That's a lot harder to do -- I can get away with scraping the front page right now because highly voted posts are likely to be on the front page for most of their vote-getting lifetime, but that argument probably doesn't hold about highly commented posts.
Hm, this is true. Perhaps you could scrape /newcomments and keep track of which stories are getting new comments?
This would hinge on the frequency of all comments to the site and having your scraping interval be less than the difference of the most recent comment and last comment displayed on /newcomments.
I think it'd just be really great to have another view into "Most active discussions".
