Actually Goitz ,

There is one other bit that I noticed that cause the demotion of posts...
I think that you mean "promotion", as it brings it back to the top of the stack

As far as I am aware the age of the original post that started the thread does not matter. It is the time/date of the last post that promotes a thread. Obviously, in the case of a new thread, this is also the first post.

Another point regarding what appears on the front page: there is a "default" for which forums appear. If a post arrives in a non-qualifying forum, you won't see it, even though it is newer than some of the 24 items that are displayed. As I mentioned earlier you can customise which forums are displayed, using the option in the Member Functions section.

I also mentioned the View More Active Topics feature, that shows you recent posts, and seems to clear down on a 24 hour cycle.

Under the Member Functions section you have another option "Mark All Forums Read" which will provoke a clearing down of this display. Threads will only reappear if they have a new post to them or if they are a new thread. This option also clears your new messages count and new antipoints message.