Javascript+Python: sending array to Python script, returning result to Javascript

Yes, totally. Check out Google App Engine to build this sort of functionality. In particular check out these links:

NLTK on App Engine: Using the Python NLTK (2.0b5) on the Google App Engine and http://code.google.com/p/nltk-gae/

Facebook API on App Engine: https://developers.google.com/appengine/articles/shelftalkers

I assume that you want to make it interactive because you mentioned the word "user".

Calling a service from Javascript is a very common problem. One way of solving it is to write a specific type of website known as a Webservice which would make the process flow something like...

• Javascript uses Ajax (Asynchronous Javascript and XML) to send an HTTP Request to your Webservice containing the information you want to process.
• The Webservice receives the request and performs the requested processing (eg by invoking the NLTK)
• The resulting data is sent back over the same Http connection
• A javascript function is called and passed the results of the data

The easiest way to send a request is using jQuery. The easiest way to format the data to be passed back and forth is JSON (JavaScript Object Notation).

An example call would look something like this...

$.json({
  url: "/url/of/Webservice",
  data: {
         "SomeKey": "SomeValue",
         "SomeList": ["Item1", "Item2", "Item3"]
         /*... etc */
        }
}).done(function(response) {
  //Assuming a response that looks like this: {"Result": "Some Result"}
  alert("The Webservice said: " + response.Result);
});

It's up to you how you'd implement the Webservice. If you want to use Python, Django is one of many good frameworks to get you started