This is not a high priority but something I've thought about from time to time. It might be nice to see the original post date of a thread alongside the original poster's name in the list of titles. It would be even nicer if that date were somehow marked (larger, smaller, different color, highlighted) to indicate that it's beyond a certain threshold - say, more than a year old.
The reason I suggest this is that it's not uncommon for someone to unwittingly reply to a very old post that has lost its relevance. I've done this myself on occasion.
I realize there are often very good reasons to revive old posts, and have nothing against that at all, I'm just trying to come up with a mechanism that would ensure that anyone doing so does it intentionally, not accidentally.