Vaughan Systems has published a serie of audio-books very interesting to learn english. The pack is formed by four audio-books.
I have purchased two of them: A Christmas Carol and Tales of Casanovas´s Memoirs. Both are fantastic tools to improve the english vocabulary, listening and the pronunciation in english.
My favourite one is, righ now, A Christmas Carol, because the story is so nice, wonderful, full of good intentions and full of important morals of a fable. But on the other hand, this story is too easy to read and understand if you know a bit of english language.
The another one, in my opinion, is more interesting in relation to the vocabulary because this story is more extense and complex and it can give us new concepts and new english words to complete our english vocabulary.