I'm currently using the following books:
Kaplan GRE & GMAT Math Workbook (3rd Edition)
Kaplan Verbal Workbook (2nd Edition)
Princeton Review's Cracking The GMAT (2007 Edition)
Kaplan GMAT Premier Program (2007 Edition)
Official Guide for GMAT Review (11th Edition)
Kaplan GMAT 800 (2006 - 2007 Edition)
The first two are not really important if your skills are not rusty. They give a very good foundation for the GMAT.
Princeton Review is the simply the best when it comes to good techniques but I found the practice questions in the book too easy.
Kaplan Premier program is substantially different from Princeton Review in relation to techniques and difficulty of questions. Although the questions in the Kaplan book are more difficult than in the Princeton Book, the questions are a piece of cake compared to their CATs!
Official Guide is a must have! The only place you'll meet the real deal!
Kaplan GMAT 800 is the book you really need if you're aiming for 700 and above.
Whatever books you get, I recommend you use them in the order listed above. Whatever you do, your main focus should be on the Official Guide!