Social share buttons based on Font Awesome (G+, Facebook, Twitter, LinkedIn, Pinterest, SU); jQuery plugin + CSS; demo: http://jsfiddle.net/jkacalak/tko8vevv/

jquery-sharify.js

$(function () {
  var shareUrl = document.location.origin + document.location.pathname;
  var knownButtons = ['google-plus', 'twitter', 'pinterest', 'facebook', 'stumbleupon', 'linkedin'];

  /**
   * jQuery plugin - create share buttons
   *
   * @param {Object} [options]
   * @param {string[]} [options.buttons] - list of share buttons to be shown
   * @param {string} [options.url] - shared URL (by default current)
   * @param {string} [options.media] - shared image (optionally used by Pinterest)
   * @param {string|boolean} [options.counter=none] - type of display for share counter (top|bottom|none)
   * @param {string} [options.className] - CSS class for the root DOM element
   */
  $.fn.sharify = function (options) {
    var settings = $.extend({
      buttons: knownButtons.slice(),
      url: document.location.origin + document.location.pathname,
      media: null,
      counter: false,
      className: ''
    }, options);

    settings.buttons.contains = function (item) {
      return this.indexOf(item) > -1;
    };

    if (settings.counter && settings.counter !== 'none' && settings.counter !== 'bottom') {
      settings.counter = 'top';
    }
    else if (!settings.counter) {
      settings.counter = 'none';
    }

    return this.each(function () {
      var $share = $('<div/>', {class: $.trim(['share', 'counter-' + settings.counter, settings.className].join(' '), settings.className)});
      $.each(settings.buttons, function (index, name) {
        if (knownButtons.indexOf(name) > -1) {
          $share.append(createButton(name, settings));
        }
      });

      enableShareClick($share, settings);
      if (settings.counter !== 'none') {
        setShareCount($share, settings);
      }
      $(this).append($share);
    });
  };

  function createButton(name, settings) {
    var $button = $('<div/>', {'class': ['button', name].join(' ')});
    switch (settings.counter) {
      case 'top':
        $button.append(
          $('<div/>', {'class': 'counter'})).append(
          $('<a/>', {'href': '#'}).append(
            $('<i/>', {class: 'fa fa-' + name}))
        );
        break;
      case 'bottom':
        $button.append(
          $('<a/>', {'href': '#'}).append(
            $('<i/>', {class: 'fa fa-' + name}))
        ).append(
          $('<div/>', {'class': 'counter'})
        );
        break;
      case 'none':
        $button.append(
          $('<a/>', {'href': '#'}).append(
            $('<i/>', {class: 'fa fa-' + name})));
        break;
    }
    return $button;
  }

  function enableShareClick($share, settings) {
    function openShareWindow(e) {
      window.open(e.href, 'mywin', 'left=20,top=20,width=500,height=400,toolbar=1,resizable=0');
      return false;
    }

    var buttons = settings.buttons;
    if (buttons.contains('twitter')) {
      $share.find(".twitter a")
        .attr("href", "//twitter.com/intent/tweet?text=" + document.title + "&url=" + settings.url)
        .on("click", function () {
          return openShareWindow(this)
        });
    }
    if (buttons.contains('facebook')) {
      $share.find(".facebook a")
        .attr("href", "//www.facebook.com/sharer/sharer.php?u=" + settings.url)
        .on("click", function () {
          return openShareWindow(this)
        });
    }
    if (buttons.contains('linkedin')) {
      $share.find(".linkedin a")
        .attr("href", "//www.linkedin.com/cws/share?url=" + settings.url)
        .on("click", function () {
          return openShareWindow(this)
        });
    }
    if (buttons.contains('pinterest')) {
      if (settings.media) {
        $share.find(".pinterest a")
          .attr("href", "//www.pinterest.com/pin/create/button/" + "?url=" + settings.url + "&media=" + settings.media)
          .on("click", function () {
            return openShareWindow(this)
          });
      }
      else { // let Pinterest resolve your Pin media
        $share.find(".pinterest a").on("click", function (ev) {
          ev.preventDefault();
          var e = document.createElement('script');
          e.setAttribute('type', 'text/javascript');
          e.setAttribute('charset', 'UTF-8');
          e.setAttribute('src', 'http://assets.pinterest.com/js/pinmarklet.js?r=' + Math.random() * 99999999);
          document.body.appendChild(e);
        });
      }
    }
    if (buttons.contains('google-plus')) {
      $share.find(".google-plus a")
        .attr("href", "//plus.google.com/share?url=" + settings.url)
        .on("click", function () {
          return openShareWindow(this)
        });
    }
    if (buttons.contains('stumbleupon')) {
      $share.find(".stumbleupon a")
        .attr("href", "//www.stumbleupon.com/badge/?url=" + settings.url)
        .on("click", function () {
          return openShareWindow(this)
        });
    }
  }

  function setShareCount($share, settings) {
    var buttons = settings.buttons;
    if (buttons.contains('twitter')) {
      $.getJSON("http://urls.api.twitter.com/1/urls/count.json?url=" + settings.url + "&callback=?",
        function (json) {
          $share.find(".twitter .counter").text(formatCount(json.count));
        });
    }
    if (buttons.contains('facebook')) {
      $.getJSON("http://graph.facebook.com/" + settings.url, function (json) {
        $(".facebook .counter").text(formatCount(json.shares));
      });
    }

    if (buttons.contains('pinterest')) {
      $.getJSON("http://api.pinterest.com/v1/urls/count.json?url=" + settings.url + "&callback=?", function (json) {
        $(".pinterest .counter").text(formatCount(json.count));
      });
    }

    if (buttons.contains('linkedin')) {
      $.getJSON("http://www.linkedin.com/countserv/count/share?url=" + settings.url + "&callback=?",
        function (json) {
          $(".linkedin .counter").text(formatCount(json.count));
        });
    }

    function formatCount(num) {
      num = num || 0;
      if (num >= 1000000000) {
        return (num / 1000000000).toFixed(1) + 'G';
      }
      if (num >= 1000000) {
        return (num / 1000000).toFixed(1) + 'M';
      }
      if (num >= 1000) {
        return (num / 1000).toFixed(1) + 'K';
      }
      return num;
    }
  };
});

style.scss

@mixin common-share-button() {
  color: white;

  a {
    color: inherit;
    display: block;
    width: 100%;
    outline: 0;
  }

  .counter {
    font: 12px "Lucida Sans Unicode", "Lucida Grande", sans-seriff;
    line-height: 1em;
    padding: 2px 0px 1px 0px;
    &:empty {
      display: none;
    }
  }
}

@mixin default-share-button($background) {
  @include common-share-button();
  background: $background;

  &:hover {
    background: lighten($background, 7%);
    .counter {
      background: darken($background, 3%);
    }
  }

  .counter {
    background: darken($background, 10%);
    &:hover {
      background: darken($background, 3%);
    }
  }
}

@mixin image-share-button($hover-background) {
  @include common-share-button();
  $background: lightgrey;
  background: $background;
  opacity: 0.8;

  &:hover {
    opacity: 1;
    background: $hover-background;
    .counter {
      background: darken($hover-background, 10%);
    }
  }

  .counter {
    background: darken($background, 10%);
    &:hover {
      background: darken($hover-background, 10%);
    }
  }
}

.share {
  .button {
    font-size: 24px;
    line-height: 1em;
    text-align: center;
    width: 40px;

    i.fa {
      padding: 6px 5px;
    }
    &.twitter {
      @include default-share-button(#5EA9DD);
    }
    &.google-plus {
      @include default-share-button(#CD3C2A);
    }
    &.pinterest {
      @include default-share-button(#BC071B);
    }
    &.facebook {
      @include default-share-button(#4966B6);
    }
    &.linkedin {
      @include default-share-button(#1783BC);
    }
    &.stumbleupon {
      @include default-share-button(#EA4B24);
    } 
  }

  &.image {
    .button {
      &.twitter {
        @include image-share-button(#5EA9DD);
      }
      &.google-plus {
        @include image-share-button(#CD3C2A);
      }
      &.pinterest {
        @include image-share-button(#BC071B);
      }
      &.facebook {
        @include image-share-button(#4966B6);
      }
      &.linkedin {
        @include image-share-button(#1783BC);
      }
      &.stumbleupon {
        @include image-share-button(#EA4B24);
      }
    }
  }
}

/*horizontal styling*/
.horizontal {
  .share {
    .button {
      display: inline-block;
      margin-right: 4px;
    }

    &.counter-top {
      .button {
        vertical-align: bottom;
      }
    }
    &.counter-bottom {
      .button {
        vertical-align: top;
      }
    }
  }
}

/* jsFiddle example */
.post {
  margin-left: 10px;
  font-family: "Lucida Sans Unicode", "Lucida Grande", sans-seriff;
  p {
    font-size: 20px;
  }
  .example {
    margin-top: 20px;    
    &.image {
      position: relative;     
      .share {
          position: absolute;
          top: 0;
          left: 0;
      }
    }
  }
}

usage_example.html

<div class="post">
    <p>Default style:</p>
    <div class="example hidden-counter"></div>
    <div class="example hidden-counter horizontal"></div>
    
    <p>Image sharing:</p>
    <div class="example image">
        <img src="http://www.adweek.com/files/uploads/iStock-Unfinished-Business-6.jpg" width="500" />
    </div>
    
    <p>Share counter top:</p>
    <div class="example counter-top"></div>
    <div class="example counter-top horizontal"></div>
    
    <p>Share counter bottom:</p>
    <div class="example counter-bottom"></div>
    <div class="example counter-bottom horizontal"></div>    
</div>

usage_example.js

$(function(){
    var buttons = ['twitter', 'google-plus', 'facebook', 'pinterest', 'linkedin', 'stumbleupon']
    
    $('.example.hidden-counter').sharify({buttons: buttons});
    $('.example.image').sharify({buttons: buttons, className: 'image', media: $('.example.image img').attr('src')});    
    $('.example.counter-top').sharify({buttons: buttons, counter: 'top'}); 
    $('.example.counter-bottom').sharify({buttons: buttons, counter: 'bottom'});
});