For example: the MongoDB libraries for Node gave us many problems. I won't go into the specifics as that would take a while, but switching to Ruby mongo driver along with the Mongoid ORM resulted in a huge increase in code readability and is much more reliable I think.
Also being able to use amazing Ruby libraries like devise/omniauth are a big win I think. Similar with Jammit, Barista, Rspec, the list goes on. Here's our current Gemfile: https://gist.github.com/68f0326a9480266d462e. Some of these libraries have Node.js equivalents, but they are all very early stage.
That said, most of our code is UI side anyways. For that I'm using coffeescript / jquery / backbone.js. We'll probably reintroduce some small, focused Node.js server components in the future for the most highly accessed http requests as we start to ramp up the traffic.
Fascinating, I remember 2-3 years back people were saying exactly the same thing, but replacing Node.js with Rails and Ruby with Python. The more things change, the more they stay the same!
Forgive me if I'm wrong, but this just doesn't exist for Rails. Sure you might find the random open source'd library or plugin, but that's about the extent of re-usable code you're going to have.
For the Django developer, in minutes you can have a website with a blog, tagging system, voting, contact form, traditional registration system, social authentication, openid logins, avatars, user profiles, friends/followers, on-site messaging, full-site search, and all ready for e-commerce. And that's just the tip of the iceberg. Any of those parts are autonomous and interchangeable. Sure it'll take a bit longer to actually configure the apps how you'd like, display them in your desired format, and connect them up according to your business logic, but who's really going to complain about that after getting all of the above for free?
Hell, for half of my clients I barely have to write a single custom line of code; their entire site request can be broken down into reusable Django apps that already exist and I've worked with before. It's the pinnacle of Don't Repeat Yourself. If that's not the ideal ecosystem for webapps then I don't know what is.
Snarky answer: "Yeah, it's called GitHub."
Real answer: I'm not sure what you're suggesting. All of these things are available as a Ruby gem, either directly or as Rack middleware.
Now http://djangoplugables.com/ is rather well organized and we don't really have a good centralized place to find them outside of github, but they exists and it's quick painless to use them...
Did you do any integration testing for scrabbly?