This is not dissimilar to other recent posts, but they seem to have all been tagged on to other threads, so I'll start a new one.
Users have often identified threads of no interest to them, whether due to the topic or nature of the thread. If you've been away for a while, and want to "trim down" the list of threads to read, the only way seems to be to open the threads you don't want, then return to "unread posts", until you've just got to the ones you want to read.
Would it be possible to provide a button to mark a single thread as "read" rather than all or nothing?