A while back, after a few urgent e-mails from my hosting provider, I turned on the rule that says “a visitor may leave a comment on this site only if they are a registered user,” but I forgot (or never knew) that I had to also turn on the rule that says “anyone with a valid e-mail address may register for an account.”
The end result, of course, was that the site told you that you had to be logged-in to leave a comment, but there was no “register for account” option.
Well, now there is. Please sign up and comment at will. All blog posts and most pages have commenting enabled.
(Credit for title: @WinstonUK)