Such as livejournal replies.
To make a long story short, I hate empty subject-lines, Gentle Readers. Those of you who have been using it when replying to entries here already have my Gratitude; those of you who will read this and start to use it will have it. Those of you who refuse to do so, will cause me to mutter briefly, then carry on with Life.
In other words, this is a Request, not a Rule. Carry on.