@designbyonyx - thank you for reading my post, Ryan!
In relation to hosting infrastructure, I've tried Heroku, AppFog and I've played around a bit with OpenShift.
Each one has its own pros and cons, but I can safely say my number one favourite is Heroku by far. Not the cheapest, but it's safe, reliable, you can run any Node.js version you like, it has a nice git-based deployment mechanism with the possibility to do rollbacks if necessary, and you can also choose among an infinity of add-ons for your apps. Plus, their now standard Node.js buildpack has a fantastic caching mechanism that will only download and install the necessary NPMs in your server environment (which means really fast deployments).
I'm not sure I understand what you mean by tips on "installing node modules". If they're on npmjs or github, Heroku will install them automatically based on
package.json. But on most PaaS providers you can deploy your
node_modules folder anyway. If your modules use native code, they might have to be compiled on the deployment environment, but again most PaaS deployment mechanisms will do it behind-the-scenes based on
If we're talking about "standard" web projects (tens to hundreds of concurrent users), there aren't many things you can't do with clustering and 1-2 Heroku web workers. For larger projects, scaling is pretty straightforward, but it also depends on your app architecture.
In relation to MongoDB, I like both MongoLab and MongoHQ.
RedHat's OpenShift is also interesting as a "general purpose" PaaS provider, you can do lots of things with it, but you'll have to do a bit of command-line hacking and configuration if you want to install a particular Node.js version for instance. But they do offer you 3 free boxes to start with...