Something I notice on forums is that when somebody reads a topic but is too busy to reply immediately, he just leaves then eventually forgets the topic, potentially missing out on very important stuff. I know I myself do it on Cemetech because it lacks a Mark Unread option. But it seems like very few people actually use such option around the community.
If you notice the options to the right above and below the topic view, you have REPLY, ADD POLL, NOTIFY then MARK UNREAD buttons.
Basically, if you read a topic it is marked as read by default, but if you click MARK UNREAD it will save it for later by marking it as unread, so you won't forget to check again and reply later.
It will also make other people happy as they won't wonder if you are ignoring them or something.
I hope this helps you foruming.