syndaemon does just that, you should take a look.

As I'm working on a really similar app for my college final project i got really interested in this plug in and grabbed it instantly to see what magic was behind this.

fetchSummary: function(doc) { // Extract the Plid

                var plid = pluribo.extractPlid(doc); // Launch XHR to get Summary

                if (plid) {

                        var req = new XMLHttpRequest();

                        req.open('GET', 'http://'+pluribo_server+'/xhr/topic/widget/'+plid+'/', true);

                        req.onreadystatechange = function (aEvt) {

                                if (req.readyState == 4) { // Render the Pluribo Panel (if successful)

                                        if (req.status == 200) { pluribo.renderPanel(doc, req.responseText); } // Otherwise Fail Silently

                                        else { /* alert("Pluribo: error loading summary\n"); */ }

                                }

                        };

                        req.send(null);

                }

But as of the above, theres not much to look at as all the magic happens server side.
So you're right... A simple fx plug in wont do it.
From their page:
"Languages and software

Nearly all of our code is written in Python, a wonderful and elegant language. We use Boto to access AWS from python. Our NLP algorithms get help from NLTK, WordNet, and SciPy. Most of our servers run Ubuntu Linux. Our API is built with Django and Apache Lucene."

Which makes me happy as I'm also using most of this stuff, and so now I know I'm on the right path.
Now if only I could get these guys to share some love...