IH needs a "subscribe to this thread" button badly!

There are so many threads with interesting discussions happening regularly on IH. But without an option to subscribe to these threads, its getting very difficult to keep track and revisit those threads again later in the day.

A simple subscribe button on a thread that notifies us whenever someone comments on it would go a long way in keeping us engaged. Agree?

Meanwhile, does anyone have any suggestion on how they are keeping track of interesting threads to revisit later? Bookmarking?