Har-Bal mode is a special dynamic EQ (or multiband ?) mode used by
http://www.har-bal.com/ (here you will find a video tutorial).
At first I was very sceptical about their program (especially as it's not available as a plugin), but if you spend some time to learn how it works, you see it really works, and not only for pseudo-mastering, but also for processing individual tracks: for dessing, treble/bass enhancing, cutting mud etc.
it's an EQ where you declare what peak and average levels you would *want* to get (based or not on analysis of commercial tracks), and it processes audio dynamically to get these levels. So much better than older EQ-cloning applications. What's the most important, it doesn't do any "auto-magic" (unless you really want it to), but simply displays graphs you may modify by hand/ear.