The problem with comments, open forums, e-mail discussion lists and other user-generated online content is that it takes work — usually a moderator or trust system — to make sure the comments stay relevant, clean and spam-free. In fact, spammers have made old Usenet groups unreadable, have flooded most e-mail inboxes, and have brought their multi-level marketing messages to every open chat room, bulletin board and online guest book they can get their digital paws on. —Mark Glaser

—Bloggers Declare War on Comment Spam, but Can They Win? (Online Journalism Review)

A good plug for Jay Allen, whose free MT-Blacklist helps me manage spam on SHU student blogs.