From Mozilla: An overview of the object-oriented capabilities of JavaScript. This covers OO concepts of classes and objects, instances, abstraction, encapsulation and polymorphism as done in JavaScript with functions and prototypal inheritance.
Douglas Crockford's presentation on Advanced JavaScript. He covers topics such as inheritance, modules, debugging, efficiency and JSON.
Although JavaScript is a class-free, object-oriented language using prototypal inheritance, it can still be used in a classical object-oriented way. Douglas Crockford compares the two inheritance-based systems, adding syntactic sugar to JavaScript to allow classical inheritance, and demonstrates a number of patterns that are not available in classical languages.
Tim explains object orientation in the context of JavaScript, covering concepts like object literal, encapsulation, inheritance using prototype, composition through association and aggregation, polymorphism. Useful read for OO-aware developers to grasp some of the potential of JavaScript.