Based on comments and poll results, seems like it gets back to the point about how much time is required for Robin to implement the ignore-user feature. If it would require a lot of time, then just put this idea on the back burner for now. If it doesn't take much time to implement, then go for it Robin.
Generally for us users, more choices = more control = good.
However, I wonder if the more complex the site becomes also eventually equates to the more things that can go wrong. Often times, keeping things simple is good design.
I understand this thread is to help Robin to decide if it is worth it or not to implement this feature, and all the very good comments definitely will help Robin decide. It sounds like if the feature is implemented, that most will not use it, eventhough more than half vote that they would like to have this ignore-user feature.