I finally added something I have always wanted on phpBB2 forums that I have seen on other forums.
You will notice when you view all of the topics in a forum that the little box before the topic title is a dark green on some topics. This is an indicator to let you know that you posted atleast once to that topic. This is an easy way to keep track of what threads you have been posting in the past. I couldn't find a mod anywhere to do this on phpBB2 so I just created it myself. It was surprisingly easy to do.
I may end up changing this to a graphic on top of the exising graphic instead of the background change.