gistfile1.js

var async = require('async');
var collections = {};
collections.model1 = require('../model/model1');
collections.model2 = require('../model/model2');
// .. infinitamente quantos desejar

var filtro = function(collection, callback){
    collections[collection].count().exec(function(err, count){
        if(err)
            return callback(err);

        var result = {}
        result[collection] = count;
        
        callback(null, result);
    });
};

async.filter(Object.keys(collections), filtro, function(err, counts){
    if(err)
        throw err;
    else
        res.render('painel/info', {
            title: 'Informações',
            subtitle: 'Geral',
            menuativo: 'info',
            numeros: counts
        });
});