Thanks, David. Since there's a number of forum categories that I never bother with (linux, for example), I like to mark-as-read from the main index page once I've looked at my regular "haunts".
It's probably simplest to overcome my probably terminal case of congenital sloth and just scroll down to the bottom of the main index page for that.
I was just hoping that adding a second link for the same thing wouldn't be a major project for the admins here.
Guess I've been spoiled by the Wilders forums, which run on different software (phpBB, I think) -- there, you can mark everything (i.e., all messages in all forums & subforums) as read from anywhere except within a topic.
(Edit) Just did my daily rounds at Wilders, and there's a couple of corrections to the last paragraph above. They use vBulletin for their forums, and the "mark-all-read" link
is accessible from within topics, just not when you're in the middle of doing a posting or reply.