ACS puts out a review book that looks like it would be very helpful. Some friends of mine had it this past semester. I leafed through it and the practice questions seemed very similar to what was on the test when I took it the semester before. If you can't find this book, just review the basics. Know your stereochemistry, basic reactions, and basic mechanisms (some of the questions ask for the correct intermediate of a reaction). Nomenclature was pretty big, and a few questions asked to identify a correct or incorrect synthesis route. There were, as someone else pointed out, questions you might have come across in lab, as well as questions about the effects of branching, chain length, and subtituents on MP,BP, acidity, etc. There were only a couple of difficult problems on the whole thing. The national average is something like 36 or 37 correct, so if you score 50 or better you're in pretty good shape. Oh, there were a lot of "rank the following in order of ______" questions too.
