You could potentially narrow it down a little bit by taking Express out of the equation. As far as I know, Express doesn't play on the browser. You could use

You could potentially narrow it down a little bit by taking Express out of the equation. As far as I know, Express doesn't play on the browser. You could use Express to serve static content or a blog or an API but you would need to supplement it with something like Backbone or Ember on the client to build something like gmail or trello. And while you could use Meteor (or, I'm sure, Derby) for a static website, that's obviously not what it's designed for. I've never tried it, though. I'm sure it would be a real beautiful experience.