Bootswatch bookmarklet

bootswatchlet.js

if($('.bootswatcher')[0]){
	$('.bootswatcher').remove();
} else {
	var $e = $('<select class="bootswatcher"><option>Amelia</option><option>Cerulean</option><option>Cosmo</option><option>Cyborg</option><option>Journal</option><option>Readable</option><option>Simplex</option><option>Slate</option><option>Spacelab</option><option>Spruce</option><option>Superhero</option><option>United</option></select>');
	var l = 1 + Math.floor(Math.random() * $e.children().length);
	var r = '<link rel="stylesheet" href="http://bootswatch.com/default/bootstrap-responsive.min.css">';
	$e.css({'z-index': '99999', 'position': 'fixed', 'top': '5px', 'right': '5px', 'opacity': '0.5'}
	).hover(
		function(){$(this).css('opacity', '1');},
		function(){$(this).css('opacity', '0.5');}
	).change(function(){
		if(!$('link.bootswatcher')[0]){
			$('head').append('<link rel="stylesheet" class="bootswatcher">' + r);
		}
		$('link.bootswatcher').attr('href', 'http://bootswatch.com/' + $(this).find(':selected').text().toLowerCase() + '/bootstrap.min.css');
	})
	.find('option:nth-child(' + l + ')').attr('selected', 'selected').end()
	.trigger('change');
	$('body').append($e);
}

More info: http://news.bootswatch.com/post/29555952123/a-bookmarklet-for-bootswatch

Have you thought about using the API rather than hardcoding the select list? This is the modified version I use.
https://gist.github.com/TuckerWhitehouse/7828718