The Official Guide to the TOEFL Test- The most reliable book made by ETS. It is a close representation of what to expect in the main exams. The practice tests at the back along with the tests on the CD are excellent practice.
Official TOEFL IBT Tests- Pocket friendly book, but the CD only has the MP3 of the test and you cannot actually answer the questions on it.
Cambridge Preparation for the TOEFL Test- This book has about 8 full length practice tests, although the material is a little more difficult, it focuses on building up your skills for the exam.
You’ll find some really excellent study material here.