>That's a good idea but very hard thing to do sadly.
I wonder why it is so hard. Yes displaying posts since last visit would be pretty troublesome (although not necessarily so if you use javascript and cookies on the client side)

wile on the server side all you need to do is adda number of posts next to board title like this I am quite sure software already keeps track of how many posts each board has.
g 300 s 340 fur 250 ....