I generally look at DevNet through the 'Posts since last visit' search, as I guess many frequent visitors do. I find it easier than going forum-by-forum. A big downside is, however, that you also get lots of topics that I can't read (a language I don't speak) or just have no interest in.
There is a "Mark all as read" button under the list, but I would really like it if there would be a small "mark as seen" link or button for each individual topic, without actually opening that topic. That way, it would be easier to prune my lists of to-reads. To take this a few steps further, it would be nice if you could also: