The new book "JavaScript: The Good Parts: Working with the Shallow Grain of JavaScript" by Douglas Crockford (O'Reilly) has got very good reviews (I certainly do not like all O'Reilly books, this is no ad...)

I use a bit Javascript too, but have never gotten too far into it and from what I read it seems that from this book you could learn some good practices about how to use Javascript as well as an overview what this language is / could be about from a higher perspective.

In fact, I think I will read the book, soon.