I don't know if it's possible to add a feature to do this, but it would be nice to know when a post prior to yours in the thread has been edited. I'm more prone to look for it, but when I'm on a thread with someone new to the site I sometimes double post (I know, I know, throw me in the brig) just so the OP will see the added information.
Just an observation/suggestion (since I'm sure you were saying, "hey, how can we load the mail server even more... lol).