PeterReader is great, but sometimes replies where it really doesn't make sense. Case in point:
http://www.geekzone.co.nz/forums.asp?forumid=90&topicid=144302
How about allowing users to include a codeword in their post to prevent him from replying a post? (#goawaypeterreader? :P) If said codeword is detected in a post, he won't reply, even if it matches whatever other rules are in place for triggering his posts.