The Japan Times Publishing is known for excellent Japanese learning materials, most notably the Genki series of textbooks. Recently, they released The Best Practice Tests for the Japanese-Language Proficiency Test N3, which includes three high-quality tests!
According to the Japan Times, questions and answers were "rigorously selected," and given their track record, you can believe it. There is even an mp3 zip download for the listening section—a welcome departure from the now-outdated-and-clunky CDs that usually accompany Japanese learning materials. But what sets this collection apart from other practice tests is the included answer sheet with commentary. This goes beyond just giving you the right answer—you also get detailed information about why something is right. For example, in the reading comprehension sections, the commentaries point out context sentences around the "target area" that you should focus on. This goes a long way toward helping you increase your knowledge and develop strategies for the next practice test (not to mention the real one).
These tests are highly recommended for those setting their sights on N3. If you follow the book's timeframes, methods, and scoring sheets for each of the three tests, you should be able to level-up three times before the big day!