Here is an idea for what I think is a new feature.
I would like to know when I am viewing a page if I already have this thread bookmarked. (It would be especially awesome if it showed in the "Recent with Pictures" view) Maybe "grey out" the tab that says "bookmark", or add a little "this thread is bookmarked" graphic somewhere?
I find that I am bookmarking the same thread several times, as I "find" it in different ways (recent, hot, linked from other threads, etc). I also find that things I thought I bookmarked aren't, and I end up missing stuff in threads I am trying to follow.