Thanks to my fantastic girlfriend, I now know an awesome trick!
If there is a threaded discussion in GMail that you want to stop hearing from (think flamewars, or a specific discussion you are not interested in on some list that you usually do want to follow…), you can "mute" that discussion. (Supposedly, if you are directly addressed in this thread, it will still deliver the message. S-M-A-R-T!)
There are keyboard nav bindings for it, but I know it is also in the "More Actions" dropdown box at the top of the screen.
What a GREAT feature! It has been saving my attention span immeasurably today!