Wow, it's encouraging to see that I have a chance at some of the top programs. I'm gonna have to do some serious thinking.
As far as prep goes, I think my background and hobbies did me a favor because I actually didn't prep. I took 1 practice exam a few days before the actual exam and got a 770, so I didn't bother getting a prep book or reading prep materials.
In college I took a lot of math classes, Calc I, II, III, Diff EQ I, II, Adv Calc I, II, Discrete Math, Combinatorics, Linear Algebra, Number Theory I, II, Applied Adv Calc I, and Introduction to topology.
In my spare time, I like to read, I go through probably 15-25 books a year.
So when I took the test, I didn't feel thrown off by any questions. Well, except one in Quant, the very last question asked about effects of how to deal with addition of new members to a set with combinations, averages, and standard deviations simultaneously. I'm guessing it didn't count because I still got a 51.