<dl>
    <dt>Simple searchbox:</dt>
    <dd><input name="search" placeholder="Search" /></dd> 
    <dt>Subscribe:</dt>
    <dd><input name="email" placeholder="Enter your email here" /></dd>
    <dt>etc.</dt>
</dl>

$(window).addEvent('domready', function()
{
	if ('placeholder' in document.createElement('input')) return;
 
	var color = '#aaa';
 
	$$('input').each(function(el)
	{
		var text = el.get('placeholder'),
		    defaultColor = el.getStyle('color');
 
		if (text)
		{
			el
				.setStyle('color', color)
				.set('value', text)
 
				.addEvent('focus', function()
				{
					if (el.value == '' || el.value == text)
					{
						el
							.setStyle('color', defaultColor)
							.set('value', '');
					}
				})
 
				.addEvent('blur', function()
				{
					if (el.value == '' || el.value == text)
					{
						el
							.setStyle('color', color)
							.set('value', text);
					}
				});
 
			var form = el.getParent('form');
			if (form)
			{
				form.addEvent('submit', function()
				{
					if (el.value == text)
						el.set('value', '');
				});
			}
		}
	});
});