Are there any projects, examples, tutorials, etc that would show ExtJS used with Node.js as the backend? I am looking specifically at multiple users collaborating in real-time, but anything with ExtJS and node together would be helpful.
Here is a example of ExtJS used with Node.js. There is another interesting project (server side javascript) called SilkJS. You should have a look at it as well. Here is an example of using SilkJs and ExtJS.
Since Node.js is server side, you should not have any issues using it along with ExtJS. There is no dependency on server side for ExtJS.
SilkJS is fast enough that it is real time; maybe more real-time than node even.
Anyhow, ExtJS does a lot of Ajax internally, FWIW.
I have done a example on Extjs with node at backend. Please go through the git