Is there a way to limit commentors from making rapid multiple posts in a short period of time? Perhaps a plugin that would check how long it has been since the person last made a comment. When I look at comment spam it often comes in bursts over a very short time. SlashDot does something like this where if I post a comment I then must wait some time period to post another. Ideally it should get longer and longer. Just recognizing IP addresses is not enough. Sometimes I see identical spam comments come in from different IP's over a short period.