main.js

//main.js
var	util = require('util');

util.debug('main initializing');
var someMod = require('./someModule').makeApp('SomeApp', 'Tom');
someMod.displayAppName();
someMod.displayUserName();

someModule.js

//someModule.js
(function() {

    var makeApp = function(appName, userName) {	
        return new App(appName, userName);
    }

    var App = function(appName, userName) {
        var util = require('util');

	this.displayAppName = function() {
		util.debug('app name: ' + appName);
	}

	this.displayUserName = function() {
		util.debug('user name: ' + userName);
	}

        // this is returned by default :(
        // also your writing to this without calling new
	//return this;
    }

    module.exports.makeApp = makeApp;

})();