"Apparently I owe about $900 for physicians that I NEVER SAW who stopped by and read my chart, or something. The insurance website claims that they paid nothing, but that my member cost should only be about $300...but whatever billing center these guys used wants all of the money."

You may be able to argue some of those charges as well, just like any other bill you receive. Perhaps I'm a skeptic, but I've heard of a lot of people being billed for bogus charges at hospitals. Sounds like you have no idea who these physicians are or what they did. At the very least, I'd find out what the heck you're paying for, and what service they provided to you. How many doctors are listed? What did they all do? If it was just consults on your chart, why were so many people needed (worries me about what the attending physician does or doesn't know!). Although never this extensive, I've contested items such as lab fees, and "extra" charges for procedures that I did indeed get reversed. There are those out there who try to take advantage of the fact that not everyone reads their bill, and those of us that do probably don't understand a lot of it.