日本語擬態語辞典 - Nihongo Gitaigo JitenLB118
An Illustrated Dictionary of Japanese Onomatopoeic Expressions)
By Gomi Taro - Kodansha ed. - ISBN code 9784062568531
Gitaigo are words that sound like what they describe - and they are prevalent in Japanese. This illustrated book by Taro Gomi (author of "Everyone Poops") makes it easy to understand what they mean. His brilliant illustrations will appeal to more people than a grammar book would, and even from a teacher's perspective, illustrating gitaigo might make more sense than trying to explain them with words.
This book is actually good for students of any level. Explanations are in English and Japanese, but for the most part the explanations are in the illustrations themselves. Beginners can spice up their speech with these fun expressions, and advanced students should definitely brush up on these - they are ultimately necessary to fully communicate well in Japanese.