SlimScroll

HTML

<div class="slim-scroll">
<ul>
    <li>Entry</li>
    <li>Entry</li>
    <li>Entry</li>
    <li>Entry</li>
    <li>Entry</li>
    <li>Entry</li>
    <li>Entry</li>
    <li>Entry</li>
    <li>Entry</li>
    <li>Entry</li>
    <li>Entry</li>
    <li>Entry</li>
    <li>Entry</li>
    <li>Entry</li>
    <li>Entry</li>
    <li>Entry</li>
    <li>Entry</li>
    <li>Entry</li>
    <li>Entry</li>
    <li>Entry</li>
    <li>Entry</li>
    <li>Entry</li>
    <li>Entry</li>
</ul>
    </div>

JavaScript

/*! Copyright (c) 2011 Piotr Rochala (http://rocha.la)
 * Dual licensed under the MIT (http://www.opensource.org/licenses/mit-license.php)
 * and GPL (http://www.opensource.org/licenses/gpl-license.php) licenses.
 *
 * Version: 1.3.0
 *
 */
(function(f){jQuery.fn.extend({slimScroll:function(h){var a=f.extend({width:"auto",height:"250px",size:"7px",color:"#000",position:"right",distance:"1px",start:"top",opacity:0.4,alwaysVisible:!1,disableFadeOut:!1,railVisible:!1,railColor:"#333",railOpacity:0.2,railDraggable:!0,railClass:"slimScrollRail",barClass:"slimScrollBar",wrapperClass:"slimScrollDiv",allowPageScroll:!1,wheelStep:20,touchScrollStep:200,borderRadius:"7px",railBorderRadius:"7px"},h);this.each(function(){function r(d){if(s){d=d||
window.event;var c=0;d.wheelDelta&&(c=-d.wheelDelta/120);d.detail&&(c=d.detail/3);f(d.target||d.srcTarget||d.srcElement).closest("."+a.wrapperClass).is(b.parent())&&m(c,!0);d.preventDefault&&!k&&d.preventDefault();k||(d.returnValue=!1)}}function m(d,f,h){k=!1;var e=d,g=b.outerHeight()-c.outerHeight();f&&(e=parseInt(c.css("top"))+d*parseInt(a.wheelStep)/100*c.outerHeight(),e=Math.min(Math.max(e,0),g),e=0<d?Math.ceil(e):Math.floor(e),c.css({top:e+"px"}));l=parseInt(c.css("top"))/(b.outerHeight()-c.outerHeight());
e=l*(b[0].scrollHeight-b.outerHeight());h&&(e=d,d=e/b[0].scrollHeight*b.outerHeight(),d=Math.min(Math.max(d,0),g),c.css({top:d+"px"}));b.scrollTop(e);b.trigger("slimscrolling",~~e);v();p()}function C(){window.addEventListener?(this.addEventListener("DOMMouseScroll",r,!1),this.addEventListener("mousewheel",r,!1),this.addEventListener("MozMousePixelScroll",r,!1)):document.attachEvent("onmousewheel",r)}function w(){u=Math.max(b.outerHeight()/b[0].scrollHeight*b.outerHeight(),D);c.css({height:u+"px"});
var a=u==b.outerHeight()?"none":"block";c.css({display:a})}function...