* [Klass](https://github.com/ded/klass) - a utility for creating expressive classes in JavaScript.
* [Oorja](http://maxpert.github.com/oorja/) - Library provides basic Class structure for Javascript. Keeps in mind the C++ style OOP.
* [Fiber](https://github.com/linkedin/Fiber)
* [My-Class](https://github.com/jiem/my-class)
* [Species](https://github.com/k33g/species) - JS Class structure, Java style OOP.
* [Proto.js](https://github.com/rauschma/proto-js) - Prototypes as classes, and read this ["prototypes as classes"](http://www.2ality.com/2011/06/prototypes-as-classes.html#more)
* [Joose](http://joose.it/)
* [JS.Class](http://jsclass.jcoglan.com/)
* [ComposeJS](https://github.com/kriszyp/compose)
* [Clasico](https://github.com/davidjbeveridge/clasico)
* [self](https://github.com/munro/self)
* [jsface](https://github.com/tnhu/jsface) - a small and fast Class system

P.S. http://habrahabr.ru/post/132698/#comment_4404597