I have come upon the situation where I see a question that really interests me.
I have nothing to add to this question at the moment, not a comment not answer but I'm particularly interested in what people have to say about this.
This leads me to think that in this situation, the favorite isn't enough.
One of the main ideas of this site is that the questions you post may help others too, so that "allows me" to be as interested as the OP in the answers and comments to that question. (Even though it's not mine).
This is why I think that the favorite doesn't "notify enough", in the case where you want to be a very active participant/viewer of the question, even though you didn't ask it yourself.
Just to clarify, you should receive the same notifications as if you had asked the question.
I realize that this is particular situation, it is not every question that you would need to do this in every question.
It would probably need another button in the SE interface, and that is a BIG change.
It may mean too much information if over used.
Despite this I think it would make a pretty good and useful feature that would benefit the site because of a greater user involvement in a question.
Thanks in advance.
EDIT: As ChrisF points out in his comment there is also the RSS feed, I'm not a big fan and I like to keep my inbox very clean, but it true that it is quite similar to what I have "requested". The difference is that this feature keeps everything on-site.
Somehow related: Please allow me to follow questions