User blog comment:Xean/What Works for Your Wiki?/@comment-26686429-20110525203609/@comment-1025281-20110526071103

Like I suggested and linked, use a "new messages" template and post on the other user's talk page to ping them when they forget that you've replied.

Of course, the way to avoid forgetting that your message has been replied to is to add the user's talk page to your watchlist. The back to basics approach. :P