Loftwings and Demons

To block someone, go to

Account Settings->Privacy->Ban and Unban

And then type in a comma-separated list of usernames to Ban. These people will no longer be able to comment on your account.

I think I will have cause to use this quite a bit in the future. I like that Dreamwidth doesn't exacerbate interpersonal problems the way Tumblr does with things like recommended posts, but people are still people and not all of us get along.