jQuery UI Selectmenu (offical, latest)

HTML

<script src="http://view.jqueryui.com/selectmenu/ui/jquery.ui.core.js"></script>
<script src="http://view.jqueryui.com/selectmenu/ui/jquery.ui.widget.js"></script>
<script src="http://view.jqueryui.com/selectmenu/ui/jquery.ui.position.js"></script>
<script src="http://view.jqueryui.com/selectmenu/ui/jquery.ui.menu.js"></script>
<script src="http://view.jqueryui.com/selectmenu/ui/jquery.ui.selectmenu.js"></script>
<link rel="stylesheet" href="http://view.jqueryui.com/selectmenu/themes/base/jquery.ui.all.css">
<link rel="stylesheet" href="http://view.jqueryui.com/selectmenu/demos/demos.css">
<form action="#">

	<fieldset>
		<label for="speed">Select a speed</label>
		<select name="speed" id="speed">
			<option value="Slower">Slower</option>
			<option value="Slow">Slow</option>
			<option value="Medium" selected="selected">Medium</option>
			<option value="Fast">Fast</option>
			<option value="Faster">Faster</option>
		</select>

		<label for="files">Select a file</label>
		<select name="files" id="files">
			<optgroup label="Scripts">
				<option value="jquery">jQuery.js</option>
				<option value="jqueryui">ui.jQuery.js</option>
			</optgroup>
			<optgroup label="Other files">
				<option value="somefile">Some unknown file</option>
				<option value="someotherfile">Some other file</option>
			</optgroup>
		</select>

		<label for="number">Select a number</label>
		<select name="number" id="number">
			<option value="1">1</option>
			<option value="2" selected="selected">2</option>
			<option value="3">3</option>
			<option value="4">4</option>
			<option value="5">5</option>
			<option value="6">6</option>
			<option value="7">7</option>
			<option value="8">8</option>
			<option value="9">9</option>
			<option value="10">10</option>
			<option value="11">11</option>
			<option value="12">12</option>
			<option value="13">13</option>
			<option value="14">14</option>
			<option value="15">15</option>
			<option value="16">16</option>
			<option...

CSS

fieldset {
    border: 0;
}
label {
    display: block;
    margin: 30px 0 0 0;
}
select {
    width: 200px;
}
.overflow {
    height: 200px;
}

JavaScript

$( "#speed" ).selectmenu();

$( "#files" ).selectmenu();

$( "#number" )
    .selectmenu()
    .selectmenu( "menuWidget" )
    .addClass( "overflow" );