Another useful DSL technique is curry-ing. From WikiPedia: Currying is the technique of transforming a function that takes multiple arguments (or an n-tuple of arguments) in such a way that it can be called as a chain of functions each with a single argument.

As a cocktail of methods for currying I've seen, I use this:

Function.prototype.curry = function( fn ){
  var slice = Array.prototype.slice;

    return function(){
        var args = slice.apply(arguments),
            master = arguments.callee,
            that = this;

        return args.length >= fn.length ? fn.apply(that,args) : function(){
            return master.apply( that, args.concat(slice.apply(arguments)) );
        };
    };
};

Basically it extends the Function prototype to allow you to write things like:

var sum = Function.curry(function( x, y ){  
    return x + y;  
});

The above can then be used to write code as follows:

sum(5)(5); // 10