It would make this forum much easier to use if you could somehow identify unread posts (by user). I have to keep scanning old posts that I've already read to see if there are any new ones. After a while, I probably won't bother.
The way wattpad does it is to have the number of unread posts per thread to the right of the thread name. So if I had read 10 posts and two more were added since I was last in that thread, the number would be "2 new posts" (2 new posts for me. Every user would have a different number). I'd then go to the bottom of the thread and scroll up 2 posts (new ones added to the end). Wattpad also numbers the posts so I could actually do the math, but the scrolling is easier than math.