Closest thing I've found is if you go to 'view recent posts', it seems to keep track of read/unread by showing the thread title in green for unread, greyed out for read. It even seems to track progress, say if you open a thread this morning and read it and do not post, it'll show greyed-out (read). but if somebody posts again, next time you look it'll be green again. I've found it to be reliable, but not 100%.
This is my primary method of reading this board. I never look at the main page with all the sections unless there is something specific I am looking for. I just go to 'view recent posts'. I start going back in time page by page for as long as I feel like browsing.
I miss the read/unread feature too but I don't mean that to sound like a complaint.
The feature I miss along with the read/unread is the ability to mark a thread as 'unread'. This comes in handy as a reminder to reply to a thread later.
Sorry this got a bit long-winded.