johnschimmel/NodeJS-with-ExpressJS-and-MongoDB — pull request #1 by cmenscher (2012-10-24 17:13:08+00:00)
Title: Heroku would not compile so added "engines" block to package.json

Heroku would not compile this app with its default Node version ("Error: Cannot find module 'zlib'"). I explicitly set Node.js to version 0.8.12 and npm version 1.1.49 with an "engines" block in package.json, and it now deploys.

This is my first foray into Node.js and Heroku...so this may not be the best solution for the missing zlib module, but it's what I found online and seems to work. So sue me. :)