[nirmal]

To be notified when someone replies to me I use Notifo (http://notifo.com/) and put my Notifo username in my HN profile. I don't think you need a mobile device to use Notifo, you can install a desktop app that provides notifications when you get a reply. http://notifo.com/desktop

[zck]

You can set email notifications up, so you don't need a mobile device or a desktop application.

[AgentConundrum]

I think I'd prefer a desktop app over email. I don't get a lot of replies here, largely due to my infrequent commenting, but I'd hate to randomly hit upon a popular comment and be flooded with 20 emails while I'm out.