Yes. You might already know about the MT-Notifier Blog Widget, but there's an MT-Notifier Entry Widget as well. This will allow your blog readers to sign up for notifications every time an entry is updated or comment is posted.
(1) Log into UThink
(2) Select your blog from the dashboard
(3) Tools > Plugins
(4) Click on MT-Notifier 4.31
(5) On the expanded window, click Settings.
(6) On the bottom of the Settings window, "Click here to install the MT-Notifier Entry Subscription Widget". That will open a new widget template that you can modify or just save.
Where Movable Type developers might have dropped the ball is here: what do you do with this widget? If you install it on your sidebar, it will show up on every page's sidebar, not just your entry pages. You could create a separate widget template set for just entry pages, but that might not be necessary. It would be better to allow it to only show up if someone is on an entry archive page (otherwise, hide it.)
Here's what I would suggest:
Save that into your widget, then install it to your sidebar like you would install any widget (Design > Widgets > 3-column layout - Primary/Secondary Sidebar)