I just noticed that when you are logged on, if you click on the user CP option on the top left, this will list the topics where you have posted all grouped together. I don't know how long it keeps this information, but mine has at least 2 days ago. After you click on user cp, when your new posts appear, there is another option in the lower right corner to see all your posts. This showed everything I have replied to. I have also noticed that when I am signed in and looking at the main forums page. a check mark appear in the topics that I have just recently posted.