I would love to be able to use **Markdown** on the forums, I think it is a good compromise between ease of use and possibilities.
Or if you don't want to add Markdown support, it would be nice to be able to quote posts (actually you can, click the Formatting button and you can select quote).
Another thing that I would like is to be able to subscribe to topics. So if you really want to follow the development of a game you receive a notification when there is a new message. If you add this feature it would also be nice to be able to customize the behaviour of the notifications, for example:
- Send an email when you have a notification
- When you post in a thread, subscribe automatically