A simple background-image slider made with jQuery and Underscore in WordPress (inserted before the closing `</body>` tag). More details here: http://www.webbyworks.com.au/41/a-simple-jquery-background-image-slider

simple-bg-slider.js

<script src="//cdnjs.cloudflare.com/ajax/libs/underscore.js/1.4.2/underscore-min.js"></script>
<script type="text/javascript">  
	jQuery(document).ready(function($) {
		// check to see if the page contains this element
		if ( $('.my-bg-slider').length > 0 ) {
			
			// insert the URIs of all the images you wish to include in the slider here:
			var backgroundImages = [ 'http://www.example.com.au/wp-content/uploads/2012/12/DSC_02461.jpg',
									'http://www.example.com.au/wp-content/uploads/2012/11/DSC_0161_1.jpg',
									'http://www.example.com.au/wp-content/uploads/2012/12/DSC_0587.jpg',
									'http://www.example.com.au/wp-content/uploads/2012/12/DSC_0293.jpg' ];
									
			// get the existing backgroundImage of the div element
			var existingImage = $('.my-bg-slider').css('background-image');
			existingImage = existingImage.replace('url(','').replace(')','');
			
			// remove the existing image from the backroundImages list (if it's there)
			var tempArr = _.without(backgroundImages, existingImage);
			// randomly shuffle the remaining images
			var randomImages = _.shuffle(tempArr);
			
			// load the new images in the background to speed up transfer
			for ( var a = 0; a < randomImages.length; a++ ) {
				$('<div class="temp-imgs">').appendTo('div.my-bg-slider').html('<img src="' + randomImages[a] + '" />').css("display", "none");
			}
			
			// insert existingImage to the front of the shuffled list
			randomImages.unshift(existingImage);
			
			var i = 0; // needs to start at the next list item (not 0)

			setInterval(function() {
				i++;
				// check to see if we're now at the end of our slider image array
				// if so, start back at the start again
				if ( i === randomImages.length ) { i = 0; }
				
				var img = "url(" + randomImages[i] + ")";
				
				// fadeOut the current image then replace the backgroundImage then fadeIn
				$('.my-bg-slider').fadeOut(1000, function() {
					$('.my-bg-slider').css('background-image', img);
				});
				$('.my-bg-slider').fadeIn(1000);
				
			}, 3500);
		}
	});
</script>