hn.profilebar.user.js

// ==UserScript==
// @name         Hacker News profile bar
// @description  Adds a profile bar to each comment that includes data from the user's profile page (e.g. karma, days since creation, "about me" text)
// @author       Shaun Gallagher, author of "Experimenting With Babies" (http://www.experimentingwithbabies.com) and "Correlated" (http://www.correlated.org)
// @namespace    HNprofilebar
// @match https://news.ycombinator.com/*
// ==/UserScript==


// load jQuery
function addJQuery(callback) {
  var script = document.createElement("script");
  script.setAttribute("src", "https://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js");
  script.addEventListener('load', function() {
    var script = document.createElement("script");
    script.textContent = "(" + callback.toString() + ")();";
    document.body.appendChild(script);
  }, false);
  document.body.appendChild(script);
}


// add a profile bar
function main() {

    user_set = [];
    users = {};
    counter = 0;
    max_gets = 50;

    $('.comhead a[href^="user"]').each(function() {
        var div = $(this).parent().parent();
        var comhead = $(this).parent();
        var user = $(this).text();
        if ($.inArray(user, user_set) == -1 && counter <= max_gets) {
            user_set.push(user);

            var about = window.localStorage.getItem('hn_about_' + user);
            var stats = window.localStorage.getItem('hn_stats_' + user);

            function insertBar(user, stats, about) {
                $('.comhead a[href="user?id=' + user + '"]').each(function() {
                    var div = $(this).parent().parent();
                    var comhead = $(this).parent();
                    $(comhead).append(stats);
                    if (about) {
                        html = $('<div style="margin-top: 5px; font-family: verdana; font-size: 8pt">' + about + '</div>');
                        $(div).append(html);
                    }
                });
            }

            if (!stats) {
                counter++;
                $.get('https://news.ycombinator.com/user?id=' + user, function(data) {

                    var about = $(data).find('textarea[name="about"]').text();
                    if (!about) {
                        about = $(data).find('td:contains("about:")').next().html();
                        about = about.replace(/<p>/g,'<br>')
                        about = about.replace(/<\/p>/g,'<br>')
                        about = about.replace(/<br>/g, ' ')
                    }
                    if (about) {
                        if (about.length > 500) {
                            about = about.substr(0, 500) + '...';
                        }
                        window.localStorage.setItem('hn_about_' + user, about);
                    }

                    var karma = $(data).find('td:contains("karma:")').next().text();
                    var avg = $(data).find('td:contains("avg:")').next().text();
                    var created = $(data).find('td:contains("created:")').next().text();
                    var stats = ' | karma: ' + karma + ' | avg: ' + avg + ' | created: ' + created;
                    window.localStorage.setItem('hn_stats_' + user, stats);

                    insertBar(user, stats, about);

                });
            }
            else {
                insertBar(user, stats, about);
            }

        }
    });
}

// load jQuery and execute the main function
addJQuery(main);

Screenshot shows the profile bars in action:

Learn how to install this user script