Man, web forums suck. No good "mark as read" at all. No "mark thread as read". No "ignore person". And you have to keep going back to them, and every different site has a different UI.
Mailing lists are a bit better, but subscription management is still a pain, and you have to set up filters manually to put all the mail somewhere.
The newsgroup interface is so the way to go. No-one has invented anything better yet IMO.