I am still working on a modification for the forums that will email you an automatic notification when a topic has been replied too by someone.
It will require you to flag the topic/post to begin with. Once you have flagged a topic and someone replies to it you will get an email notification to the email you used to sign up at this site.
I was working on it and I am about 1/2 way done with it, but had to set it aside temporarily. I am hoping to finish it up and test it over the next week.