can you list the original posting date on the front page?
Maybe next to the OP's name? Sometimes extremely old threads get revived (how or why, I can't fathom), or a side conversation will pop up in a thread that was originally looking for restaurant recommendations for a vacation that was years ago. New posts will come up, and it's sometimes not until you've opened it or even responded that you realize it's totally moot. (By "you" I mean "I," of course.) I'd rather not have to open a post to see if someone still needs to know where to have lunch in Portland or if the lunch happened in 2007.
This is something that many hounds have been requesting for YEARS, to no avail, despite the several site reformulations that have happened in the meantime. Another one that has been ignored is some kind of flag to indicate when a thread has a new reply that is responding to a thread comment by the particular reader. If an old or very long thread has a new post, you would likely want to read it if it referred to YOUR contribution to that thread, but you'd be pretty annoyed to open a 400-post-long thread just to find that the new post was a "LOL" or "+1" referring to someone else's post.