Is there a way to get an email notification when some replies to a topic I'm interested in?

Yes... if you go to the FAQs section which is here, it will tell you how to do this. Look at the topic "How do Watch Lists Work?"

Are you talking about here in the Forums?

At the top of each thread there should be a drop-menu called "topic options". If you click on that one of the options is "Add Topic to your Watched Topics".

To receive emails about responses to these, you need to click at the top of the Forums page where it says "My Stuff" and then click on "Edit Preferences" from the list of items on the left-hand side of the page.

Go down to the option that says "By default should anything added to your Watch Lists be emailed to you?" and make sure that the "yes" radio buttin is selected. Click the "Submit" button at the bottom of the page to save your changes.

Thank you. I missed the button in Edit Preferences. I had even clicked "Do you want to be notified via email when you receive a private message?" but I overlooked "By default should anything added to your Watch Lists be emailed to you?.