Since the OO aspect of JavaScript is often overlooked, here's a text about Object Hierarchy and Inheritance in JavaScript.
I myself have been a fan of this approach to OO since my first encounters with prototype-based OO languages like Self and NewtonScript - the pigeonhole thinking of class-based OO approaches is often restrictive, especially when modeling real-world objects.
By the way, JavaScript also has a whole lot of other nice features that are often overlooked - first and foremost the nice anonymous functions, through which Closures in JavaScript are realized. And higher-order programming can also be implemented with it.
If you now combine Prototype-OO and Higher-Order-Programming, something like Prototype might come out - a library for JavaScript with a lot of interesting extensions such as elegant Ajax bindings, simpler callback construction and many other toys. Another possibility could arise from Bob Ippollitos MochiKit, if it is ever published (and lives up to the hype).
Prototype, by the way, requires a lot of imagination as to what can be done with it - there is no documentation after all.