I highly recommend Kaplan's "Math for Nurses" book. The book is broken down into 2 parts. The first one is "Foundation Skills" and is exactly what it says... a review of the simpler math topics. The second part is the "Applications" section and goes into detail about what nurses need to know. I have to tell you this book became my best friend and I am no longer intimidated of math thanks to it. It tells you how to do dosage calculations for oral, IV, and parental medications. It was a lifesaver. I think the best thing about it is that early on, it introduces you to 3 or 4 different math approaching strategies... if you don't like one, move on until you find one that works for you. Then, for every type of problem in the book, it shows you how to use EACH strategy to find out the answer. It rocks!
The ISBN is 978-1-4195-9955-2
I got mine at Barnes and Noble for about 15 bucks I think and it was worth every penny.