There are two things that every site would love, viz. visitors and return visitors, the latter preferably and participaters.
While the commenting system within WordPress allows participation to some extent, it does lack a lot of features, one particularly being the ability for visitors to receive updates on their comments.
Users can subscribe to comments on a particular post, either while they are commenting or seperately without comment, if you choose to enable this option.
Whenever a new comment is then posted, the subscribed users receive an email with the details of the comment, including content.
They can unsubscribe at anytime via the link in their email or you can choose to unsubscribe them. They can also block their email from receiving any updates on a global basis.
STC still has a few features lacking and Mark hopes to correct them with the next release.
For one, there is no way to view the users who are subscribed. However, Maxpower has a plugin that lets you view this information.
I would also like to see the ability to mass unsubscribe users as well unsubscribing post-wise instead of just email-wise.
The reason is that I have noticed that quite a few emails are incorrect ones, resulting in bounces (I just unsubscribed 15 junk emails from a single post yesterday).
Lastly, the ability to mail all the subscribed users at one go would be useful. I’m planning on doing the same as did Everton.