Exportación

file_1.js

var connect = function ( config ){ 
  this.db	= mongo.createConnection( config.url );
};

// Mis metodos..
// y mas funciones necesarias

exports.Connect = connect;

file_master.js

// Iniciando proceso

GLOBAL.connection = require('./file_1.js');
GLOBAL.db = new connection.Connect( 'mongo://localhost:2781/MiDB' );
var routes = require('./file_method.js');
var express = require('express');
var app = express();

// Metodo de uso
// db.collection...

app.post('/upload', routes.upload);

file_method.js

exports.upload = funciton(res, req){
  db.collection(..);
};