I think it would be nice if the Forums could incorporate a heavier use of the RSS system.
I'm thinking along the lines of getting RSS feeds from say a specific thread, or my visitor messages.
Reason: There are two reasons it'd be nice to bring some more RSS focus to the forums.
1) At the moment, the only RSS feed available on the forums pretty much only alerts your RSS reader of new threads created. It doesn't send sync feeds to say those newly created threads have been updated or anything like that, just when new ones are made.
2) "Subscribe to this thread" that is built into the forums doesn't work at all. I have subscribed to many different threads setting notification from "Instant e-mail" right up to the various time interval digests. I never ever receive any notifications though.
Wouldn't be too bad to have it work with Forum PM syncs either. I got on today and apparently if you have more than 1 PM come in since last time you logged in, you won't be notified upon login.