Good study materials for Pre-Calc all the way up to Diff Eq would be the Schaum's Outline books. They have a '3000 Solved Problems in Calculus' book that is great for practice just because of the sheer amount of problems. They have a great Linear Algebra outline too with lots of solved problems...
I am not taking the Math Subject GRE until April 2013, but I have found that Schaum's Outlines are good for just practice problems. Especially for Calculus, they have a '3000 Solved Problems in Calculus' book that goes from Pre-Calc all the way up to Diff Eqs. Any Schaum's Outline book is good...