Yup, i really like how the js community doesn't hate on other frameworks/libraries, but instead they use each other's ideas to better their own.

React is the "View", so you need something like Backbone to fuel it. Roll your own, use Backbone, Flux (made by FB especially for React) or Reflux (third party. Flux re-imagined).

You don't need another framework to build apps with React. But you will need several libraries as React isn't "kitchen sink" type framework like Ember and Angular.

In my React-based apps, I typically include react-router for routing and request or superagent for ajax calls. You can also include a Flux-inspired library if you're into that sort of thing.

React + Flux in the form of Flummox (along with react-router for routing) is enough for a 10kloc application I recently wrote for Expedia. If you don't want to make architectural decisions or composing smaller libraries then I think Ember is a better choice, but for us React is perfect.

The only thing you need is Ajax and you have it right here in the browser without the need of a third party library. All the rest can be handled by React and its plugins.

That's how I do things, React + raw Xml Http requests. Since JSX is already a layer on its own no need to add yet another layer of complexity.

Just pure react is great for tiny things, but for large applications you should use React with Flux architecture with alt or flummox or reflux or whatever you like, it simplifies things in the long run.

Of course you would need to do things like ajax or routing, for which there are endless libraries, or you can just go pure XHR. React-Router is terrific for routing.