application.js

// application.js
$(function(){
	$('body').removeClass('js-disabled').addClass('js-enabled');
	
	$('#i_like_this').incrementILikeCount();
});

$.fn.incrementILikeCount = function() {
	return this.each(function(){
		var	linkAction = $(this).attr('href')
		$(this).click(function(){
			var commentCount = $('h3#article_like_count span')
			var linkText = $(this).parent();
			$.get(linkAction,function(){
				commentCount.text(parseInt(commentCount.text(),10)+1);
				linkText.fadeOut('fast',function(){
					$(this).text('Thanks for your vote');
				});
				linkText.fadeIn('fast');	
			});
			return false; 
		});
	});
}

articles_controller.rb

// article_controller.rb
def like
  article = Article.find(params[:id])
  article.update_attribute(:likes, (article.likes + 1))
  render :nothing => true
end

show.html.erb

//articles => show.html.erb
<%= content_tag :h3, link_to("I like this!", {:controller => :articles, :action => :like, :id => @article}, :id => "i_like_this") %>

<%= content_tag :h3, pluralize_likes(@article.likes), :class => "comment_count", :id => "article_like_count" %>