Its annoying to have to think of looking up regularily/weekly for the next episode available.
Or you even forget about it.
This is the idea of a comfortable way to watch the next episode.
I think its kinda the subscribing thing you already offer, but its not like following one guy, but a series.
Every week/time a new episode is available you should get an email with the weekly new torrents for that series or all series you "follow"/favorite/whatever.