Resources for Vocabulary BuildingBooks, apps, and websites to help you improve your Mandarin vocabulary
Schaum's Outline of Chinese Vocabulary (Yanping Xie and Duan-Duan Li): For intermediate-level students, this book contains a well-designed course of 200 exercises to help students understand and memorize practical vocabulary, including topics like computer terminology that are neglected in many other Mandarin sources.
The Pleco Chinese Dictionary (iPhone/iPad and Android) has helpful paid add-ons like a flashcard system, which includes HSK vocabulary lists with characters (both simplified and traditional) and pinyin. HSK stands for Hànyǔ Shuǐpíng Kǎoshì (汉语水平考试), a widely used test of Chinese proficiency.
Wikipedia’s HSK page also has a number of useful links.
Chinese Breeze (汉语风) is a well-reviewed and widely used series of 60 "graded readers" for students at 8 different levels of proficiency, ranging from the beginning 300-word vocabulary level to 4500 words. Carefully designed to introduce practical new vocabulary at a reasonable pace, they offer great practice material to help you review and consolidate what you've learned so far while adding new words to your vocabulary. The physical format comes with an MP3 CD (not a regular CD) to accompany the text; as of October 2012, the much cheaper Kindle format (with no accompanying audio) apparently doesn't work on Amazon's own Kindle e-readers but does work in the Kindle app on Android and Apple devices. The first book in the series is Wrong, Wrong, Wrong!