Gist is a fast and accurate summarizer for the web. It provides a simple floating/custom button that you can add to your site for free. Check out an example here.

The simplest way to use gist is to just include the javascript on page. It creates a floating button by default.

                
                    <!-- Gist BEGIN !-->
                        <script type="text/javascript" src="http://gist.sudo.me/dist/gist-mini.js"></script>
                        <script>
                            gistWizard({
                            'floatingGistButtonPos' : 150
                            });
                        </script>
                    <!-- Gist END !-->
                
            

Or, You could create your button and call the gist api.

                
                    <!-- The param to the function is for the size of the summarized content , Ex : 5 sentences -->
                    <input type="button" onclick="getGist(5);" value="gist"/>
                
            

Here are the customization parameters in the gist api.

                
                    <script>
                        gistWizard({
                            // The vertical position of the floating gist button
                            'floatingGistButtonPos' : 30,
                            // The font size of the summary
                            'defaultGistSummaryFontSize' : 'small',
                            // Choose to use the default button or specify your own or both
                            'useFloatingGistButton' : true
                        });
                    </script>