There is a really nice plugin called Subscribe to Comments which lets people do that and get updates on comments via email. And you can view the stats at the back end.

How it works is it adds a field called subscribe with name, value, etc all as subscribe . Now I'm sure cforms will work with the plugin if I could only add this field but there is no way to add a field with title, name and value for checkbox = subscribe

It will be really great if there were some way to get the two plugins to work together. Thanks!!

I searched and found that I had to turn on: Use custom input
field NAMES & ID's and ad id:subscribe

However as soon as I did this my comment form stopped working and it kept telling me that I hadn't entered the name. The name was entered so I have no idea why it mucked it up completely.