Search for BOOKISH SAVANT on Facebook... they have a great collection of quality books & review materials for English As a Second Language (ESL)including TOEFL & IELTS.

You can download books with audio files for FREE.

Here's one link I got from there for English Vocabulary enrichment, one crucial factor to pass any English test:

http://www.filefactory.com/file/b2b466a/n/Vocabulary_Princeton_-_Word_Sm...

This e-book & audio is superb! you will like it.

Good luck ^_^