kind.js

// Just do this : (and include backbone.js)
var Kind = function() {
    this.initialize && this.initialize.apply(this, arguments);
};
Kind.extend = Backbone.Model.extend

//Simpler

var Thing = function() {};
Thing.extend = Backbone.Model.extend

use.kind.js

// Use it :

var Human = Kind.extend({
	toString : function() { console.log("hello : ", this); },
	initialize : function (name) {
		console.log("human constructor");
		this.name = name
	}
});

//Someone inherits of Human
var SomeOne = Human.extend({
	initialize : function(name){
		//call parent constructor
		SomeOne.__super__.initialize.call(this, name);
	}
});

var Bob = new Human("Bob");
Bob.toString();

var Sam = new SomeOne("Sam");
Sam.toString();

use.thing.js

// Use it :

var Human = Thing.extend({
	toString : function() { console.log("hello : ", this); },
	constructor : function Human (name) {
		console.log("human constructor");
		this.name = name
	}
});

//Someone inherits of Human
var SomeOne = Human.extend({
	constructor : function SomeOne (name){
		//call parent constructor
		SomeOne.__super__.constructor.call(this, name);
	}
});

var Bob = new Human("Bob");
Bob.toString();

var Sam = new SomeOne("Sam");
Sam.toString();

you.want.static.members.js

//Static members

var Human = Kind.extend({
	toString : function() { console.log("hello : ", this); },
	initialize : function (name) {
		console.log("human constructor");
		this.name = name
	}
},{ //Static
	counter : 0,
	getCounter : function() { return this.counter; }    
});