a little off topic, but what book weighs 30 pounds?
I presume this is the older ADC-equipped display, correct? It would be rather unsightly, but couldn't you put a piece of tape across the hinge and stick the ends to the back of the display? that would keep the hinge from going beyond a certain point. might it also be possible to tighten some screw on the hinge to make it stiffer? i don't have one here so i can't look to see what's back there. Other than that, i don't know what you could do short of replacing all or part of the hinge (Apple sells the hinge as a service part, but whether or not you can find a place that will sell you a service part sans-service is another question).
hope something there helps
-max