Heh. You have no idea how much time we've spent thinking about this. :-)
I'm not a programmer nor would I have any idea how to achieve it from tracking a poster, but couldn't tracking a favorite thread be as simple as utilizing the option to place the 'dot' to mark that you have posted in that thread ... w/o actually having posted in it? That would save the trouble with some people posting in that thread only as a means to bookmark. Perhaps that could be a red dot....
So, right where it says 'Add New Post', there could be an additional option to 'Mark as Favorite', perhaps? I guess from my perspective, it seems simple enough as it would basically use / duplicate existing code.
Another feature that would be nice to see, would be a button where when we pressed it, it would bring up the recent post from a specific set of people. I have seen it called Dev Tracker on other sites. One could click on the button or link and would just bring up the official posts (say from Vic, Lisa, Gary or any of the fine people at Paizo). This way someone could just get the official posts on the paticular threads.