Not sure if this is possible, (or if it's already there, and cannot see it), but is it possible to have a mark all posts as read section in each forum.
For example, you've read / posted on the welcome page. Then later on, someone kindly also welcomes 12 people, I may not want to read them all again, but have to open each one again, to unmark it, so I can see the newer ones easily.
Or even if there's a few posts you have no need in reading, so you read and reply to your ones, then want to mark rest as read, so you can easily identify new posts again.
Just a thought, no real issue.