app.js

var router = require('router.js');

app.route = function (path, map) {
    ['get', 'post', 'put', 'delete'].forEach(function (method) {
        if (typeof map[method] !== 'undefined') {
            app[method](path, map[method]);
        }
    });
}

app.route('/path', router);

router.js

module.exports = {
    get: function (req, res) { ... },
    post: function (req, res) { ... }
};